Distally Expanding Facet Joint Implant And Delivery Device

ABSTRACT

A distally expanding facet joint implant and delivery device for distally distracting a facet joint. The facet joint implant generally includes an outer part and an inner part. The outer part includes a pair of opposed distally expandable facet plates connected by a hinge. The inner part includes a wedge that is selectively movable against the facet plates to distally expand and contract the facet joint implant into open and closed states. Teeth on the outer part engage indents on the inner part to maintain the facet joint implant in the distally expanded state. The outer and inner parts include outer and inner connectors, and the delivery device includes corresponding outer and inner connectors adapted to be in locked engagement with the outer and inner connectors to hold the implant and selectively cause it to distally expand and contract.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/653,010 filed on Oct. 15, 2019 which issues on May 11, 2021 as U.S.Pat. No. 11,000,384 (Docket No. ALJA-009). Each of the aforementionedpatent applications is herein incorporated by reference in theirentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable to this application.

BACKGROUND Field

Example embodiments in general relate to a distally expanding facetjoint implant and delivery device for distracting the joint betweenfacets of adjacent vertebrae of the spine, including cervical vertebrae,to provide nerve root decompression, maintain or improve vertebralalignment, and enhance spinal stability.

Related Art

Any discussion of the related art throughout the specification should inno way be considered as an admission that such related art is widelyknown or forms part of common general knowledge in the field.

Spine degeneration is a major burden to society. The current growth ofthe aging population is linked to a rise in cases of age-related spinejoint degenerative change or arthropathy, which is a leading cause ofchronic neck and back pain. The socioeconomic costs of degenerativespine disease are large. Such costs include both direct costs, such aspayments for treatment of pain and neurologic disorders, and indirectcosts from loss of work and frequent sick leaves.

The spinal column is composed of 33 vertebrae, separated byintervertebral discs and held together with ligaments and muscles. Thespinal column provides an axial support for the human body in additionto its function as a protector to the spinal cord and its emerging nerveroots. Movement within each spine segment (adjacent superior andinferior vertebrae) is facilitated by the anteriorly locatedintervertebral discs and two posterior facet joints. The series of thesejoints between adjacent vertebrae of the spinal column permit thecomplex flexible movements of the spinal column.

The aging process often leads to degenerative changes that impact thestructure of the spine joints. The process involves dehydration of theintervertebral discs resulting in reduction of disc height.Subsequently, friction between the joint surfaces occurs and a processof degeneration and local inflammation begins. The joints then becomestiffer and the ligaments become thickened and less elastic. The overallprocess is collectively named spondylosis. Spondylosis leads toreduction in the size of the neural foramens (the space where the nervesemerge from the spinal cord), disc herniation, and spinal stenosisresulting in axial neck and/or back pain and neurological compromise. Asthe degenerative changes advance and the intervertebral foramennarrowing progresses, compression of the nerve roots can occur leadingto nerve damage. Such damage often manifests itself as numbness andweakness due to motor and sensory function loss in addition topersistent pain in what is called radiculopathy. Radiculopathy resultingfrom damage to the cervical nerve roots is referred to more particularlyas cervical radiculopathy.

The main goal in treating radiculopathy is to decompress the affectednerve. This goal can be accomplished by direct nerve decompression andremoval of the compressing element, or by distracting the inter-facetjoints between adjacent superior and inferior vertebrae compressing thenerve. The two approaches are frequently combined. Typically, either ananterior procedure is performed that involves the removal of thecollapsed intervertebral disc and replacement with a bone or syntheticcage, or a posterior procedure that involves laminectomy with or withoutfacetectomy (facet removal). In either case, the procedure is oftencoupled with the addition of instrumentation between the involvedvertebrae to stabilize them and facilitate their fusion together.

With respect to the cervical spine in particular, evidence hashighlighted the importance of maintaining the natural cervical spinealignment during surgical treatment of cervical radiculopathy asmaintaining the natural alignment is often associated with betterneurological functional outcomes. Thus, surgical treatment of thecervical spine to counteract the effects of the degenerative processmust incorporate cervical alignment to achieve the most beneficialoutcome.

At the same time, the current trend is to employ minimally invasivesurgical approaches to treat various spinal diseases because suchapproaches have been demonstrated to lead to less post-operative pain,less surgical blood loss, and earlier recovery from surgery. Fortreatment of cervical radiculopathy, the commonly performed minimallyinvasive technique utilizes the posterior approach and speciallydesigned devices to distract the facet joint by inserting an implantinside the facet joint and, consequently, relieving the nerve rootcompression.

A number of different facet joint implants and delivery devices havebeen proposed. However, to date nearly all such implants have limitedsuccess in providing optimal distraction of a facet joint and, when usedin a cervical facet joint, maintaining the natural lordosis andpreventing excessive kyphosis of the cervical spine.

There thus remains a need for a facet joint implant that is distallyexpandable to distract the facet joints of affected adjacent superiorand inferior vertebrae to decompress the neural foramens and relieve thesymptoms of cervical radiculopathy and, when used with a cervical facetjoint, to also maintain or improve proper cervical alignment. A devicethat expands more anteriorly when inserted in the facet joint is morelikely to achieve anterior facet joint distraction, intervertebral spacedistraction, and widening of the intervertebral foramen in addition tocorrecting existing spondylolisthesis. There also remains a need forsuch an implant and a delivery device that are readily usable withminimally invasive, posterior surgical techniques, and that can be usedand deployed while minimizing undesirable damage to the soft tissuearound the facet joint. There also remains a need for such an implantand delivery device that are less complex, easier to manipulate and use,and more readily result in the implant being properly positioned andoriented in the facet joints of affected vertebrae. There furtherremains a need for such an implant that is more reliable in achievingits intended function despite having a smaller size that facilitatesinsertion inside the relatively limited facet joint space. There furtherremains a need for such an implant and delivery device wherein theplacement and expansion of the implant is more readily and easilyreversible. There still further remains a need for such an implant thatadheres effectively to the facet bones of affected vertebrae, thatfacilitates post-operative bone fusion, and that effectively stabilizesthe spine and prevents undesirable inter-facet movement. There stillfurther remains a need for such an implant and delivery tool that arerelatively simple, easy, and inexpensive to manufacture and assemble.

The example embodiments of a distally expanding facet joint implant anddelivery device described herein seek to address these needs withrespect mainly for cervical facet joints.

SUMMARY

An example embodiment is directed to a distally expanding facet jointimplant and delivery device. The distally expanding facet joint implantincludes an outer part and an inner part. The outer part includes afirst facet plate, a second facet plate, and a hinge. The first facetplate has a first distal end portion, a first proximal end portion, anda first opening between the first distal end portion and the firstproximal end portion. The second facet plate has a second distal endportion, a second proximal end portion, and a second opening between thesecond distal end portion and the second proximal end portion. The hingeconnects the first proximal end portion of the first facet plate and thesecond proximal end portion of the second facet plate.

The inner part is at least partially exposed in the first opening andthe second opening and includes a wedge-shaped engagement structure witha third distal end portion and a third proximal end portion. The innerpart is movable relative to the outer part.

When the inner part is moved toward the first distal end portion of thefirst facet plate and the second distal end portion of the second facetplate, the distal end portion of the wedge engages the first facet plateand the second facet plate, the first distal end portion of the firstfacet plate and the second distal end portion of the second facet platemove apart, and the first proximal end portion of the first facet plateand the second proximal end portion of the second facet plate rotate onthe hinge in a first direction until the facet joint implant assumes adistally expanded open state.

When the inner part is moved toward the first proximal end portion ofthe first facet plate and the second proximal end portion of the secondfacet plate, the first distal end portion of the first facet plate andthe second distal end portion of the second facet plate move toward eachother, and the first proximal end portion of the first facet plate andthe second proximal end portion of the second facet plate rotate on thehinge in a second direction until the facet joint implant assumes adistally contracted closed state.

According to one aspect of the example embodiments, the outer and innerparts comprise first and second monolithic structures and are formed ina pre-assembled arrangement.

According to another aspect of the example embodiments, the first facetplate has a first exterior surface with a first plurality of serrationsor spikes and the second facet plate has a second exterior surface witha second plurality of serrations or spikes. The serrations or spikesfacilitate the facet joint implant adhering to the bony surfaces of thefacets adjacent to a facet joint in which it is implanted when it is inthe open state.

According to another aspect of the example embodiments, the first facetplate has a first interior surface with a first sloped portion, thesecond facet plate has a second interior surface with a second slopedportion, and the wedge has a third exterior surface with a third slopedportion and a fourth exterior surface with a fourth sloped portion. Whenthe inner part of the facet joint implant is moved toward the firstdistal end portion of the first facet plate and the second distal endportion of the second facet plate, the third sloped portion of the thirdexterior surface of the wedge engages the first sloped portion of thefirst interior surface of the first facet plate, and the fourth slopedportion of the fourth exterior surface of the wedge engages the secondsloped portion of the second interior surface of the second facet plateto cause the first distal end of the first facet plate and the seconddistal end of the second facet plate to expand apart until the facetjoint implant assumes the distally expanded open state.

According to another aspect of the example embodiments, the outer partof the facet joint implant includes a first set of teeth and the innerpart of the facet joint implant includes at least a first set of indentsand a second set of indents. When the facet joint implant is in theclosed state, the first set of teeth engage the first set of indents andwhen the facet joint implant assumes the distally contracted closedstate, the first set of teeth engage the second set of indents. Thishelps hold the facet joint implant in the open or closed position andcan provide physical feedback when the facet joint implant assumes theopen and closed positions.

According to yet another aspect of the example embodiments, the outerpart of the facet joint implant includes a first delivery deviceinterface and the inner part includes a second delivery deviceinterface. The first delivery device interface includes a firstconnector that is configured to selectively receive, be brought intoengagement with, and be brought into locked engagement with acorresponding first connector of a delivery device. When the firstconnector is in locked engagement with the corresponding firstconnector, the facet joint implant is held in a fixed position andorientation relative to the delivery device. The second delivery deviceinterface comprises a second connector that is configured to selectivelyreceive, be brought into engagement with, and be brought into lockedengagement with a corresponding second connector of a delivery device.When the second connector is in locked engagement with the correspondingsecond connector, motion can be selectively imparted to the inner partof the facet joint implant relative to the outer part of the facet jointimplant to distally expand and contract the facet joint implant.

The delivery device adapted for use with the distally expanding facetjoint implant has a distal end portion and a proximal end portion. Thedelivery device includes a corresponding first connector at the distalend portion that is configured to be brought into engagement with, beinserted in, and be brought into locked engagement with the firstconnector of the facet joint implant and when in locked engagement tohold the facet joint implant in a fixed position and orientationrelative to the delivery device. The delivery device includes acorresponding second connector at the distal end portion that isconfigured to be brought into engagement with, be inserted in, and bebrought into locked engagement with the second connector of the facetjoint implant. When the corresponding second connector is in lockedengagement with the second connector of the facet joint implant, thedelivery device is operable to selectively impart motion to the innerpart of the facet joint implant relative to the outer part of the facetjoint implant to distally expand and contract the facet joint implant.According to another aspect of the example embodiments, the deliverydevice includes an outer tube control knob that is coupled to an outertube of the delivery device. The outer tube control knob is configuredand is operable to advance the outer tube relative to the correspondingfirst connector of the delivery device and the first connector of thefacet joint implant to ensure that the corresponding first connector andthe first connector are brought into engagement and locked engagementonly in proper alignment, and with surfaces of the first connector insecure engagement with support surfaces on the outer tube.

According to another aspect of the example embodiments, the deliverydevice includes a control handle located at the proximal end portion ofthe delivery device. The control handle is coupled with thecorresponding first connector of the delivery device and is configuredand operable to selectively bring the corresponding first connector intolocked engagement with the first connector of the facet joint implant.

According to another aspect of the example embodiments, the deliverydevice includes an inner shaft control knob located at the proximal endportion of the delivery device. The inner shaft control knob is coupledwith the corresponding second connector of the delivery device and isoperable to selectively bring the corresponding second connector intoand out of engagement with the second connector of the facet jointimplant.

According to another aspect of the example embodiments, the deliverydevice includes a lock switch and a lock located at the proximal endportion of the delivery device. The lock switch is coupled with thecorresponding second connector of the delivery device, and is configuredand operable to selectively rotate the corresponding second connectorbetween a first position wherein the corresponding second connector isnot in locked engagement with the second connector of the facet jointimplant, and a second position wherein the corresponding secondconnector is in locked engagement with the second connector. The lock isresponsive to operation of the lock switch to hold or maintain thecorresponding second connector in the second position wherein thecorresponding second connector is in locked engagement.

There has thus been outlined, rather broadly, some of the embodiments ofthe distally expanding facet joint implant and delivery device in orderthat the detailed description thereof may be better understood, and inorder that the present contribution to the art may be betterappreciated. There are additional embodiments of the distally expandingfacet joint implant and delivery device that will be describedhereinafter and that will form the subject matter of the claims appendedhereto. In this respect, before explaining at least one embodiment ofthe distally expanding facet joint implant and delivery device indetail, it is to be understood that the distally expanding facet jointimplant and delivery device are not limited in their application to thedetails of construction or to the arrangements of the components setforth in the following description or illustrated in the drawings. Thedistally expanding facet joint implant and delivery device are capableof other embodiments and of being practiced and carried out in variousways. Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of the description and should not beregarded as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will become more fully understood from the detaileddescription given herein below and the accompanying drawings, whereinlike elements are represented by like reference characters, which aregiven by way of illustration only and thus are not limitative of theexample embodiments herein.

FIG. 1A is a perspective view of a distally expanding facet jointimplant in a closed state in accordance with an example embodiment.

FIG. 1B is a perspective view of a distally expanding facet jointimplant in an open state in accordance with an example embodiment.

FIG. 2A is a side view of a distally expanding facet joint implant in aclosed state in accordance with an example embodiment.

FIG. 2B is a side view of a distally expanding facet joint implant in anopen state in accordance with an example embodiment.

FIG. 3A is a top view of a distally expanding facet joint implant in aclosed state in accordance with an example embodiment.

FIG. 3B is a top view of a distally expanding facet joint implant in anopen state in accordance with an example embodiment.

FIG. 4A is a bottom view of a distally expanding facet joint implant ina closed state in accordance with an example embodiment.

FIG. 4B is a bottom view of a distally expanding facet joint implant inan open state in accordance with an example embodiment.

FIG. 5A is a distal end view of a distally expanding facet joint implantin a closed state in accordance with an example embodiment.

FIG. 5B is a distal end view of a distally expanding facet joint implantin an open state in accordance with an example embodiment.

FIG. 6A is a proximal end view of a distally expanding facet jointimplant in a closed state in accordance with an example embodiment.

FIG. 6B is a proximal end view of a distally expanding facet jointimplant in an open state in accordance with an example embodiment.

FIG. 7A is a top cross-sectional view of a distally expanding facetjoint implant in a closed state in accordance with an exampleembodiment.

FIG. 7B is a top cross-sectional view of a distally expanding facetjoint implant in an open state in accordance with an example embodiment.

FIG. 8A is a side cross-sectional view of a distally expanding facetjoint implant in a closed state in accordance with an exampleembodiment.

FIG. 8B is a side cross-sectional view of a distally expanding facetjoint implant in an open state in accordance with an example embodiment.

FIG. 9A is an exploded first perspective view of a distally expandingfacet joint implant in a closed state showing a distally expanding outerpart and an inner part with wedge-shaped engagement structure of theimplant in accordance with an example embodiment.

FIG. 9B is an exploded second perspective view of a distally expandingfacet joint implant in a closed state showing a distally expanding outerpart and an inner part with wedge-shaped engagement structure of theimplant in accordance with an example embodiment.

FIG. 9C is an exploded perspective view of the inner part of a distallyexpanding facet joint implant in accordance with an alternative exampleembodiment.

FIG. 9D is a perspective view of a second or inner connector of theinner part of a distally expanding facet joint implant in accordancewith an alternative example embodiment.

FIG. 9E is a perspective view of a second or inner connector of an innerpart and a first or outer connector of an outer part of a distallyexpanding facet joint showing threaded engagement between the secondconnector and first connector in accordance with an alternative exampleembodiment.

FIG. 10 is a perspective view of a delivery device for use with adistally expanding facet joint implant in accordance with an exampleembodiment.

FIG. 11 is a side view of a delivery device for use with a distallyexpanding facet joint implant in accordance with an example embodiment.

FIG. 12 is a top view of a delivery device for use with a distallyexpanding facet joint implant in accordance with an example embodiment.

FIG. 13 is a side cross-sectional view of a delivery device for use witha distally expanding facet joint implant in accordance with an exampleembodiment.

FIG. 14 is a top cross-sectional view of a delivery device for use witha distally expanding facet joint implant in accordance with an exampleembodiment.

FIG. 15 is an enlarged detail side view of the distal end portion of adelivery device for use with a distally expanding facet joint implant inaccordance with an example embodiment.

FIG. 16 is a distal end view of a delivery device for use with adistally expanding facet joint implant in accordance with an exampleembodiment.

FIG. 17 is a proximal end portion cross-sectional view of a deliverydevice for use with a distally expanding facet joint implant inaccordance with an example embodiment.

FIG. 18 is a proximal end view of a delivery device for use with adistally expanding facet joint implant in accordance with an exampleembodiment.

FIG. 19 is a distal end portion cross-sectional view of a deliverydevice for use with a distally expanding facet joint implant inaccordance with an example embodiment.

FIG. 20 is an exploded perspective view of a delivery device for usewith a distally expanding facet joint implant showing the components ofthe delivery device in accordance with an example embodiment.

FIG. 21 is a perspective view of a distally expanding facet jointimplant and the distal end of a delivery device for use with the implantshowing the implant and delivery device aligned for connection inaccordance with an example embodiment.

FIG. 22A is a perspective view of a distally expanding facet jointimplant and a delivery device for use with the implant showing thedelivery device and an outer part of the implant being brought intolocked engagement in accordance with an example embodiment.

FIG. 22B is a partially transparent enlarged detail perspective view ofa distally expanding facet joint implant and the distal end of adelivery device for use with the implant showing the delivery device andan outer part of the implant being brought into locked engagement inaccordance with an example embodiment.

FIG. 23A is a perspective view of a distally expanding facet jointimplant and a delivery device for use with the implant showing thedelivery device and an inner part of the implant being brought intoengagement in accordance with an example embodiment.

FIG. 23B is a partially transparent enlarged detail perspective view ofa distally expanding facet joint implant and the distal end of adelivery device for use with the implant showing the delivery device andan inner part of the implant being brought into engagement in accordancewith an example embodiment.

FIG. 23C is a partially transparent enlarged detail perspective view ofa distally expanding facet joint implant and the distal end of adelivery device for use with the implant showing the delivery device andan inner part of the implant being brought into engagement in accordancewith an example embodiment.

FIG. 23D is a perspective view of a distally expanding facet jointimplant and a delivery device for use with the implant showing thedelivery device and an inner part of the implant being brought intolocked engagement in accordance with an example embodiment.

FIG. 23E is a partially transparent enlarged detail partial perspectiveview of a distally expanding facet joint implant and the distal end of adelivery device for use with the implant showing the delivery device andan inner part of the implant in locked engagement in accordance with anexample embodiment.

FIG. 24A is a side view of a distally expanding facet joint implant anda delivery device for use with the implant showing the delivery deviceand an inner part of the implant in locked engagement in accordance withan example embodiment.

FIG. 24B is a top cross-sectional view of a distally expanding facetjoint implant and a delivery device for use with the implant showing thedelivery device and an inner part of the implant in locked engagement inaccordance with an example embodiment.

FIG. 24C is an enlarged detail view of a proximal end portion of thedistally expanding facet joint implant and a distal end portion of thedelivery device for use with the implant as shown in FIG. 24B showingthe delivery device and the inner part of the implant in lockedengagement in accordance with an example embodiment.

FIG. 24D is a cross-sectional view of a proximal end portion of thedistally expanding facet joint implant and a distal end portion of thedelivery device for use with the implant as shown in FIG. 24A showingthe delivery device and the inner part of the implant in lockedengagement in accordance with an example embodiment.

FIG. 25A is a perspective view of a distally expanding facet jointimplant and a delivery device for use with the implant showing thedelivery device in locked engagement with an inner part of the implantand the inner part being translated into a distally expanding outer partof the implant in accordance with an example embodiment.

FIG. 25B is a partially transparent enlarged detail partial perspectiveview of a distally expanding facet joint implant and the distal end of adelivery device for use with the implant showing the delivery device inlocked engagement with an inner part of the implant and the inner partbeing translated into a distally expanding outer part of the implant inaccordance with an example embodiment.

FIG. 26A is a side view of a distally expanding facet joint implant anda delivery device for use with the implant showing the delivery devicein locked engagement with an inner part of the implant, the inner parttranslated into a distally expanding outer part of the implant, and theimplant in an open state in accordance with an example embodiment.

FIG. 26B is a top cross-sectional view of a distally expanding facetjoint implant and a delivery device for use with the implant showing thedelivery device in locked engagement with an inner part of the implant,the inner part translated into a distally expanding outer part of theimplant, and the implant in an open state in accordance with an exampleembodiment.

FIG. 26C is an enlarged detail view of a proximal end portion of thedistally expanding facet joint implant and a distal end portion of thedelivery device as shown in FIG. 26B showing the delivery device inlocked engagement with the inner part of the implant, the inner parttranslated into the distally expanding outer part of the implant, andthe implant in the open state in accordance with an example embodiment.

FIG. 26D is a cross-sectional view of a proximal end portion of thedistally expanding facet joint implant and a distal end portion of thedelivery device for use with the implant as shown in FIG. 26A showingthe delivery device in locked engagement with the inner part of theimplant, the inner part translated into the outer distally expandingpart of the implant, and the implant in the open state in accordancewith an example embodiment.

FIG. 27A is a perspective view of an inter-facet connection plate foruse with a distally expanding facet joint implant in accordance with anexample embodiment.

FIG. 27B is a top view of an inter-facet connection plate for use with adistally expanding facet joint implant in accordance with an exampleembodiment.

FIG. 27C is a side view of an inter-facet connection plate for use witha distally expanding facet joint implant in accordance with an exampleembodiment.

FIG. 28A is a perspective view of a distally expanding facet jointimplant and an inter-facet connection plate in accordance with anexample embodiment showing the implant in a closed state positioned in afacet joint between adjacent cervical facets.

FIG. 28B is a perspective view of a distally expanding facet jointimplant and an inter-facet connection plate in accordance with anexample embodiment showing the implant in an open state positioned in afacet joint between adjacent cervical facets.

FIG. 29A is a partial perspective view of a distally expanding facetjoint implant with an inter-facet connection plate and a delivery devicein accordance with an example embodiment showing a step in a process ofimplanting the implant in a facet joint between adjacent cervicalfacets.

FIG. 29B is a partial perspective view of a distally expanding facetjoint implant with an inter-facet connection plate in accordance with anexample embodiment showing another step in a process of implanting theimplant in a facet joint between adjacent cervical facets.

FIG. 29C is a side view of a distally expanding facet joint implant withan inter-facet connection plate in accordance with an example embodimentshowing still another step in a process of implanting the implant in afacet joint between adjacent cervical facets.

FIG. 29D is a perspective view of a distally expanding facet jointimplant with an inter-facet connection plate in accordance with anexample embodiment showing still another step in a process of implantingthe implant in a facet joint between adjacent cervical facets.

FIG. 29E is a partial perspective view of a distally expanding facetjoint implant with an inter-facet connection plate and a delivery devicein accordance with an example embodiment showing yet another step in aprocess of implanting the implant in a facet joint between adjacentcervical facets.

DETAILED DESCRIPTION

Example embodiments of a distally expanding facet joint implant anddelivery device embodying the concepts of the present invention aredescribed below with reference to the foregoing figures.

A. Overview.

Example embodiments of a distally expanding facet joint implantgenerally include a facet joint implant 10 having an outer part 12 andan inner part 14. The facet joint implant 10 has an open state in whichit is distally expanded and a closed state in which it is distallycontracted. The inner part 14 is movable relative to the outer part 12to cause the facet joint implant 10 to distally expand to the open stateand to distally contract to the closed state.

The outer part 12 includes a first facet plate 20, a second facet plate30, a hinge 38, a first set of teeth 40, and a first or outer connector51. The first facet plate 20 has a first distal end portion 21, a firstproximal end portion 22, and a first opening 23 between the first distalend portion 21 and the first proximal end portion 22. The second facetplate 30 has a second distal end portion 31, a second proximal endportion 32, and a second opening 33 between the second distal endportion 31 and the second proximal end portion 32. The hinge 38 connectsthe first proximal end portion 22 of the first facet plate 20 and thesecond proximal end portion of the second facet plate 30.

The first facet plate 20 has a first exterior surface 24 with a firstplurality of serrations 25 and the second facet plate 30 has a secondexterior surface with a second plurality of serrations 35.Alternatively, the serrations can be replaced by projections or spikes.When the facet joint implant 10 is implanted in a facet joint and in thedistally expanded open state, the first plurality of serrations 25 andthe second plurality of serrations 35 help adhere the facet jointimplant to the bony surfaces of the facets adjacent to the facet jointso that the facet joint implant 10 does not move in the facet joint andthe facet joint and adjacent facets are strengthened and stabilized. Thebone of the facets also can grow into the first plurality of serrations25 and the second plurality of serrations 35 and through the firstopening 23 in the first facet plate 20 and the second opening 33 in thesecond facet plate to help fuse the facets adjacent to the facet jointand further improve the strength and stability of the facet joint andthe surrounding facets.

The inner part 14 includes a wedge 61 with a third distal end portion 62and a third proximal end portion 63, a second or inner connector 81, anelongated connector 70 connecting the second connector 81 and the wedge61, and a first set of indents 73 and a second set of indents 74 formedon the elongated connector 70. The inner part 14 is movable relative tothe outer part 12 and is at least partially exposed in the first opening23 of the first facet plate 20 and the second opening 33 of the secondfacet plate 30.

When the inner part 12 is caused to move toward the first distal endportion 21 of the first facet plate 20 and the second distal end portion31 of the second facet plate 30, the third distal end portion 62 of thewedge 61 engages the first facet plate 20 and the second facet plate 30.This in turn causes the first distal end portion 21 of the first facetplate 20 and the second distal end portion 31 of the second facet plate30 to move apart until the facet joint implant 10 reaches the distallyexpanded open state. As the first distal end portion 21 of the firstfacet plate 20 and the second distal end portion 31 of the second facetplate 30 move apart, the first proximal end portion 22 of the firstfacet plate 20 and the second proximal end portion 32 of the secondfacet plate 30 rotate on the hinge 38 in a first direction.

In the distally expanded open state, the first set of teeth 40 on theouter part 12 of the facet joint implant 10 engage the second set ofindents 74 on the elongated connector 70 of the inner part 14 of thefacet joint implant 10, provide physical feedback, and help maintain thefacet joint implant 10 in the open position.

When the inner part 12 is moved toward the first proximal end portion 22of the first facet plate 20 and the second proximal end portion 32 ofthe second facet plate 30, the first distal end portion 21 of the firstfacet plate 20 and the second distal end portion 31 of the second facetplate 30 move toward each other until the facet joint implant 10 reachesthe distally contracted closed state. As the first distal end portion 21of the first facet plate 20 and the second distal end portion 31 of thesecond facet plate 30 move toward each other, the first proximal endportion 22 of the first facet plate 20 and the second proximal endportion 32 of the second facet plate 30 rotate on the hinge 38 in asecond direction opposite to the first direction.

In the distally contracted closed state, the first set of teeth 40 onthe outer part 12 of the facet joint implant 10 engage the first set ofindents 74 on the elongated connector 70 of the inner part 14 of thefacet joint implant 10, provide physical feedback, and help maintain thefacet joint implant 10 in the closed position.

The first or outer connector 51 of the outer part 12 is configured to beselectively engaged by and brought into locked engagement with acorresponding first or outer connector 100 of a delivery device 90 tohold the facet joint implant 10 in a fixed orientation relative to thedelivery device for introduction into the body of a patient, delivery toa facet joint in which the facet joint implant 10 is to be implanted,and insertion and positioning in the facet joint. The second or innerconnector 81 of the inner part 14 of the facet joint implant 10 isconfigured to be selectively engaged by and brought into lockedengagement with a corresponding second or inner connector 110 of thedelivery device 90 to impart motion to the inner part 14 of the facetjoint implant 10, and more specifically the wedge 61, relative to theouter part 12 of the facet joint implant 10, and more specifically thefirst facet plate 20 and the second facet plate 30. The first or outerconnector 51 and the second or inner connector 81 are arrangedconcentrically with the first connector 51 extending around the secondconnector 81.

Example embodiments of the delivery device 90 for use with the distallyexpanding facet joint implant 10 generally include a distal end portion92 and a proximal end portion 93, an elongated hollow outer tube 91, thecorresponding first or outer connector 100, and the corresponding secondor inner connector 110. The corresponding first connector 100 and thecorresponding second connector 110 are located at the distal end portion92 of the delivery device 90.

The delivery device 90 also includes an elongated hollow inner tube 105that extends from the corresponding first connector 100 to the proximalend portion 93 and an elongated inner shaft 115 that extends from thecorresponding second connector 110 to the proximal end portion of thedelivery device 90.

The delivery device 90 also includes an outer tube control knob 116, acontrol handle 120, an inner shaft control knob 121, and a lock switch124 and lock 126. The outer tube control knob 116, control handle 120,inner shaft control knob 121, and lock switch 124 and lock 126 arelocated at the proximal end portion 93 of the delivery device 90.

The corresponding first connector 100 and the corresponding secondconnector 110 are arranged concentrically with the corresponding firstconnector 100 extending around the corresponding second connector 110.The corresponding first connector 100 and the corresponding secondconnector 110 are at least partially contained within the hollow outertube 91. The inner tube 105 and the inner shaft 115 are at leastpartially contained within the hollow outer tube 91 and are arrangedconcentrically with the inner shaft 115 being contained at leastpartially in the inner tube 105.

The outer tube control knob 116 is coupled with the hollow outer tube 91and is configured and operable to advance the outer tube 91 relative tothe corresponding first connector of the delivery device and the firstconnector of the facet joint implant so that when the correspondingfirst connector and the first connector are brought into lockedengagement, surfaces of the first connector are brought into secureengagement with support surfaces on the outer tube.

The control handle 120 is coupled with the corresponding first connector100 and is operable to bring the corresponding first connector 100 intoengagement with the first connector 51 of the facet joint implant 10 byinserting the corresponding first connector 100 into the first connector51. The control handle 120 is also configured and operable to bring thecorresponding first connector 100 into locked engagement with the firstconnector 51 by rotating the corresponding first connector 100 relativeto the first connector 51.

The inner shaft control knob 121 is rotatably connected to the controlhandle 120 and is coupled with the corresponding second connector 110 bya threaded coupling 122 with the inner shaft 115. The inner shaftcontrol knob 121 rotates on the threaded coupling 122 relative to theinner shaft 115. The inner shaft control knob 121 is configured and isoperable to be selectively rotated to cause the corresponding secondconnector 110 to move toward the distal end portion 92 and the proximalend portion 93 of the delivery device 90, depending on the direction inwhich it is rotated. When the inner shaft control knob 121 is rotated ina first direction the corresponding second connector 110 moves towardthe distal end portion 92 and into engagement with the second connector81 of the facet joint implant 10. When the inner shaft control knob 121is rotated in a second opposite direction the corresponding secondconnector 110 moves toward the proximal end portion 93 and out ofengagement with the second connector 81.

The lock switch 124 is coupled with the inner shaft 115 and via theinner shaft 115 with the corresponding second connector 110. The lockswitch 124 includes a lever 125 that is rotatable between a first(unlocked) position and a second (locked) position on the control handle120. Rotation of the lever 125 between the first (unlocked) position andthe second (locked) position correspondingly rotates the correspondingsecond connector 110. When the corresponding second connector 110 is inengagement with the second connector 81 of the facet joint implant 10,rotating the lever 125 from the first (unlocked) position to the second(locked) position brings the corresponding second connector 110 intolocked engagement with the second connector 81. The lock 126 isresponsive to rotation of the lever 125 to the second (locked) positionto temporarily hold or lock the corresponding second connector 110 inlocked engagement with the second connector 81.

With the first connector 51 of the facet joint implant 10 in lockedengagement with the corresponding first connector 100 of the deliverydevice 90 and the second connector 81 of the facet joint implant 10 inlocked engagement with the corresponding second connector 110 of thedelivery device 90, the delivery device 90 can be manipulated tointroduce the facet joint implant 10 into the body of a patient, guideit to a facet joint 140 in which it is to be implanted, and insert andposition it within the facet joint 140.

Once the facet joint implant 10 is positioned in the facet joint 140,rotating the inner shaft control knob 121 further in the first directioncauses the inner part 14 of the facet joint implant 10, and morespecifically the wedge 61, to move distally relative to the outer part12, and more specifically the first facet plate 20 and the second facetplate 30, and causes the facet joint implant 10 to distally expand toits open position. Rotating the inner shaft control knob 121 in thesecond opposite direction causes the inner part 14 to move proximallyrelative to the outer part 12 and causes the facet joint implant 10 todistally contract to its closed position.

B. Outer Part.

Illustrated primarily in FIGS. 1A through 9B, the outer part 12 of thedistally expanding facet joint implant 10 comprises a first facet plate20, a second facet plate 30, a hinge 38, a first set of teeth 40, aconnecting shoulder 41, and a first delivery device interface 50.

Preferably, the outer part 12 comprises a first monolithic structure inwhich all of the components are formed or fabricated together as asingle structure. For example, the outer part 12 may be formed orfabricated using a suitable 3D printing method such as selective lasermelting (SLM). Alternatively, suitable molding techniques can beemployed. Also alternatively, one or more of the components of the outerpart 12 can be fabricated separately via SLM, other 3D printingtechniques, and/or suitable molding or machining processes, and can thenbe interconnected with the other components of the outer part 12 in anysuitable manner.

Also preferably, the outer part 12 and the inner part 14 described beloware formed at the same time, for example using a suitable 3D printingmethod such as SLM, and also are formed pre-assembled as illustrated inFIGS. 1A, 1B, and others. Alternatively, the outer part 12 and the innerpart 14 may be separately fabricated and assembled as illustrated in thefigures.

1. First and Second Facet Plates.

The first facet plate 20 and the second facet plate 30 of the distallyexpanding facet joint implant 10 are configured and are operable toengage the bony surfaces of the superior and inferior facets 143, 145 ofa facet joint 140 and to distally expand and distally distract the facetjoint 140 when the facet joint implant 10 is distally expanded.

The first facet plate 20 of the outer part 12 has a first distal endportion 21, a first proximal end portion 22, and a first opening 23between the first distal end portion 21 and the first proximal endportion 22. The first facet plate 20 has a first exterior surface 24with a first plurality of serrations 25 and a first interior surface 26.

The first interior surface 26 is generally opposed to a second interiorsurface 36 of second facet plate 30 described below. Preferably, atleast a portion of the first interior surface 26 comprises a firstsloped portion 27. Preferably, the first sloped portion 27 extendsupwardly from the direction of the first distal end portion 21 of thefirst facet plate 20 toward the first proximal end portion 22 of thefirst facet plate 20. The first sloped portion 27 is adapted to beengaged by a third sloped portion 65 of a third exterior surface 64 ofthe wedge 61 of the inner part 14 of the facet joint implant 10 asdescribed below.

The second facet plate 30 of the outer part 12 has a second distal endportion 31, a second proximal end portion 32, and a second opening 33between the second distal end portion 31 and the second proximal endportion 32. The second facet plate 30 has a second exterior surface 34with a second plurality of serrations 35 and a second interior surface36.

The second interior surface 36 is generally opposed to the firstinterior surface 26 of the first facet plate 20 described above.Preferably, at least a portion of the second interior surface 36comprises a second sloped portion 37. Preferably, the second slopedportion 37 extends upwardly from the direction of the second distal endportion 31 of the second facet plate 30 toward the second proximal endportion 32 of the second facet plate 30. The second sloped portion 37 isadapted to be engaged by a fourth sloped surface 67 of a fourth exteriorsurface 66 of the wedge 61 of the inner part 14 of the facet jointimplant 10 as described below.

The first opening 23 of the first facet plate 20 and/or the secondopening 33 of the second facet plate 30 at least partially expose theinner part 14. As will become apparent, this facilitates bone growththrough and around the facet joint implant 10 to help fuse the superiorand inferior facets 143, 145 adjacent to the facet joint 140 in whichthe facet joint implant 10 is implanted, and to thus strengthen andstabilize the facet joint 140 and the adjacent facets 143, 145. It alsofacilitates observation of the movement of the inner part 14 of thefacet joint implant 10 relative to the outer part 12 of the facet jointimplant 10, for example to confirm proper operation of the facet jointimplant 10 prior to insertion and deployment.

The facet joint implant 10 has a closed position or state and an openposition or state. Throughout the description herein, the terms“position” and “state” are employed interchangeably in this regard.

In the closed state, the first distal end portion 21 of the first facetplate 20 and the second distal end portion 31 of the second facet plate30 are in close proximity, and the first interior surface 26 of thefirst facet plate 20 and the second interior surface 36 of the secondfacet plate 30 are in close proximity and approximately parallel. FIGS.1A, 2A, 3A, 4A, 5A, 6A, 7A, and 8A among others illustrate the facetjoint implant 10 in the closed state.

In the open state, the first distal end portion 21 of the first facetplate 20 and the second distal end portion 31 of the second facet plate30 are spaced apart, and the first interior surface 26 of the firstfacet plate 20 and the second interior surface 36 of the second facetplate 30 are also spaced apart distally and at an acute angle. FIGS. 1B,2B, 3B, 4B, 5B, 6B, 7B, and 8B among others illustrate the facet jointimplant 10 in the open state.

The first plurality of serrations 25 on the first exterior surface 24 ofthe first facet plate 20 and the second plurality of serrations 35 onthe second exterior surface 34 of the second facet plate 30 areconfigured and operable to engage the bony surfaces of the superior andinferior facets 143, 145 facing the facet joint 140 respectively whenthe facet joint implant 10 is positioned in the facet joint 140 anddistally expanded in the open state or position. Alternatively or inaddition to the first plurality of serrations 25 and the secondplurality of serrations 35, spikes or other protrusions may be employed.The first plurality of serrations 25 and the second plurality ofserrations 35 help the facet joint implant 10 to adhere to the bonysurfaces of the superior and inferior facets 143, 145, to preventmovement of the facet joint implant 10 within the facet joint 140, andto stabilize and strengthen the facet joint 140 and the adjacentsuperior and inferior vertebrae. These effects are further enhanced asbone from the adjacent facets 143, 145 grows into the first and secondpluralities of serrations 25, 35.

The first facet plate 20 and the second facet plate 30 of the exampleembodiments are illustrated as being approximately rectangular in shapeand as having the same shape and dimensions. However, persons skilled inthe art will appreciate that the first facet plate 20 and the secondfacet plate 30 may be formed with various shapes and dimensions, andthat the shapes and dimensions of the first facet plate 20 and thesecond facet plate 30 may be different, provided the shapes anddimensions are suitable to achieve the objectives identified herein.Similarly, in the example embodiments the first opening 23 in the firstfacet plate 20 and the second opening 33 in the second facet plate 30have the same shape and dimensions and extend to the first proximal endportion 22 of the first facet plate 20 and to the second proximal endportion 32 of the second facet plate 30 respectively as illustrated inFIGS. 1A, 1B, 3A, 3B, 4A, 4B, and others. However, persons skilled inthe art will appreciate that the first opening 23 and the second opening33 may have various shapes and dimensions provided the shapes anddimensions are suitable to achieve the objectives identified herein.Persons skilled in the art also will appreciate that the first opening23 need not necessarily extend to the first proximal end portion 22 ofthe first facet plate 20 but may be completely enclosed by the firstexterior surface 24 of the first facet plate 20, and that the secondopening 33 need not necessarily extend to the second proximal endportion 32 of the second facet plate 30 but may be completely enclosedby the second exterior surface 34 of the second facet plate 30.

2. Hinge.

The hinge 38 connects the first proximal end portion 22 of the firstfacet plate 20 and the second proximal end portion 32 of the secondfacet plate 30. The hinge 38 is preferably positioned between the firstproximal end portion 22 of the first facet plate 20 and the secondproximal end portion 32 of the second facet plate 30. Preferably thehinge 38 is formed as a single monolithic structure with the first facetplate 20 and the second facet plate 30. Preferably the hinge 38comprises a living hinge. Alternatively, the hinge 38 can be formed as aseparate structure and attached or connected to and between the firstproximal end portion 22 of the first facet plate 20 and the secondproximal end portion 32 of the second facet plate 30 in any suitablemanner.

In the example embodiments, the hinge 38 extends across substantiallythe entire width of the first proximal end portion 22 of the first facetplate 20 and the second proximal end portion 32 of the second facetplate 30 except where it is interrupted by the first opening 23 in thefirst facet plate 20 and the second opening 33 in the second facet plate30. Persons skilled in the art will appreciate that the hinge 38 neednot necessarily extend across substantially the entire width of thefirst proximal end portion 22 of the first facet plate 20 and the secondproximal end portion 32 of the second facet plate 30 in allapplications, however, and that it may be provided at select pointsbetween the first proximal end portion 22 of the first facet plate 20and the second proximal end portion 32 of the second facet plate 30 asdesired for various applications.

The hinge 38 has a third opening 39. The third opening 39 is shaped andconfigured to allow an elongated connector 70 of the inner part 14 toextend through the third opening 39 and to move distally and proximallyrelative to the first facet plate 20 and the second facet plate 30 ofthe outer part 12 as described below.

When the first distal end portion 21 of the first facet plate 20 and thesecond distal end portion 31 of the second facet plate 30 expand apart,the first proximal end portion 22 of the first facet plate 20 and thesecond proximal end portion 32 of the second facet plate 30 rotate inopposite directions around the axis of the hinge 38. In the exampleembodiments, the first proximal end portion 22 of the first facet plate20 rotates clockwise about the axis while the second proximal endportion 32 of the second facet plate 30 rotates counter-clockwise aboutthe axis.

Accordingly, the first proximal end portion 22 of the first facet plate20 and the second proximal end portion 32 of the second facet plate 30remain in close proximity as the first distal end portion 21 of thefirst facet plate 20 and the second distal end portion 31 of the secondfacet plate 30 expand apart. The first proximal end portion 22 of thefirst facet plate 20 and the second proximal end portion 32 of thesecond facet plate 30 remain in close proximity even when the facetjoint implant 10 is in the open state.

3. First Set of Teeth.

In the example embodiments, the first set of teeth 40 are adapted andconfigured to selectively engage a first set of indents 73 and a secondset of indents 74 on the inner part 14 of the facet joint implant 10 tosecurely hold the facet joint implant 10 in a selected position ofdistal expansion as further described below. More specifically, thefirst set of teeth 40, the first set of indents 73, and the second setof indents 74 are configured, are relatively positioned, and areoperable to function like a ratchet to help hold the inner part 14 ofthe facet joint implant 10 in one of two selected positions relative tothe outer part 12 of the facet joint implant 10, and hence the facetjoint implant 10 in one of two selected states or positions of distalexpansion.

For example, the first set of teeth 40, the first set of indents 73, andthe second set of indents 74 are preferably positioned relative to oneanother so that when the facet joint implant 10 is in the closed state,the first set of teeth 40 is engaged with the first set of indents 73 tohelp hold the facet joint implant 10 in the closed state. When the facetjoint implant 10 is in the distally expanded open state, the first setof teeth 40 is engaged with the second set of indents 74 to help holdthe facet joint implant 10 in the open state.

In the example embodiments, the first set of teeth 40 is formed as partof a first set of elongated fingers 44 having distal end portions 45 andproximal end portions 46. The first set of teeth 40 is formed at thedistal end portions 45 of the first set of elongated fingers 44 with onetooth of the first set of teeth 40 formed on the distal end portion 45of each elongated finger of the first set of elongated fingers 44. Theproximal end portions 46 of the first set of elongated fingers 44 areattached or connected to a distal end portion 42 of the connectingshoulder 41 of the outer part 12 of the facet joint implant 10. In theexample embodiments, the distal end portion 42 of the connectingshoulder 41 abuts and is attached or connected to the hinge 38 of theouter part 12. The connecting shoulder 41, the first set of elongatedfingers 44, and the first set of teeth 40 are stationary relative tomovement of the inner part 14 of the facet joint implant 10.

The elongated fingers of the first set of elongated fingers 44 extenddistally from the distal end portion 42 of the connecting shoulder 41preferably along the surfaces of opposite lateral sides 75 of theelongated connector 70 of the inner part 14 of the facet joint implant10. The first set of teeth 40, and more specifically each tooth of thefirst set of teeth 40, faces inwardly toward and extends into contactwith the surfaces of the opposite lateral sides 75 of the elongatedconnector 70, including the first set of indents 73 and the second setof indents 74, which are formed in the surfaces of the elongatedconnector 70.

The elongated fingers of the first set of elongated fingers 44 areformed and configured to be deformable and elastic so that the teeth ofthe first set of teeth 40 apply a force against the surfaces of theelongated connector 70 with which they are in contact. Preferably theforce is insufficient to substantially impede movement of the inner part14 of the facet joint implant 10 relative to the outer part 12 of theimplant when the first set of teeth 40 are not engaged with either thefirst set of indents 73 or the second set of indents 74 on the elongatedconnector 70. At the same time, the force preferably is sufficient sothat when the teeth of the first set of teeth 40 encounter the indentsof either the first set of indents 73 or the second set of indents 74,the teeth are caused to securely engage and seat in the indents and tosecurely (but not irreversibly) hold the inner part 14 of the facetjoint implant 10 in position relative to the outer part 12 of the facetjoint implant 10. It is also preferred that the force be sufficient toproduce a physical feedback, such as a clicking feel or sound, when theteeth engage and seat in the indents.

This in turn securely (but not irreversibly) holds the facet jointimplant 10, and more specifically the first facet plate 20 and thesecond facet plate 30 of the outer part 12 of the facet joint implant10, in one of two selected positions of distal expansion, which asdescribed above may correspond to the closed state and the open state ofthe facet joint implant 10. The secure holding provided by the first setof teeth 40 and second set of indents 74 is particularly beneficial whenthe facet joint implant 10 is deployed in a facet joint 140 in thedistally expanded open state. In that circumstance, the facet jointimplant 10 can be subjected to substantial forces from the vertebraeadjacent the joint. The secure holding provided by the first set ofteeth 40 and second set of indents 74 helps prevent the facet jointimplant 10 from possibly inadvertently distally contracting and perhapsmoving within the joint 140 or even being ejected, especially if aninter-facet connection plate, such as described below, is not used.

At the same time, and as also described below, the holding forceprovided by the first set of teeth 40 and at least the second set ofindents 74 may or may not be so great as to prevent manually disengagingthe first set of teeth 40 from the second set of indents 74, andmanually causing the facet joint implant 10 to distally contract. Forexample, if it is deemed desirable or necessary to be able to repositionthe facet joint implant 10 in the facet joint 140 or to remove it fromthe facet joint 140 once it has been distally expanded, the second setof indents 74 can be configured to permit the first set of teeth 140 tobe manually disengaged from the second set of indents 74 by theapplication of a degree of force so that the facet joint implant 10 canbe manually distally contracted. Alternatively, however, the indents 74and teeth 40 can be made deeper or can be otherwise configured tosubstantially prevent the first set of teeth 40 from being disengaged,and thus substantially prevent the facet joint implant 10 from beingdistally contracted once it has been distally expanded.

It is preferred that the first set of teeth 40 of the outer part 12, andthe first set of indents 73 and second set of indents 74 of the innerpart 14 be at least partially visible through the first opening 23 inthe first facet plate 20 and/or the second opening 33 in the secondfacet plate 30. This facilitates observation of the movement of thefirst set of teeth 40 relative to the lateral sides 75 of the elongatedconnector 75, the first set of indents 73, and the second set ofindents, for example to confirm proper operation of the facet jointimplant 10 prior to insertion and deployment.

Preferably the first set of teeth 40, the first set of elongated fingers44, and the connecting shoulder 41 are formed as a single monolithicstructure with the other components of the outer part 12 of the facetjoint implant 10. Alternatively, one or more of the first set of teeth40, the first set of elongated fingers 44, and the connecting shoulder41 be formed as a separate structure or structures, and can be attachedor connected with the other components of the outer part 12 in anysuitable manner.

In the specific example embodiments illustrated, the first set of teeth40 comprises a first set of two teeth and the first set of elongatedfingers 44 comprises a first set of two elongated fingers with one toothformed on each elongated finger. In addition, in the specific exampleembodiments illustrated, two sets of indents 77, 78 are provided onopposite lateral sides of the elongated connector 70. However, personsskilled in the art will appreciate that depending on particularcircumstances and intended applications of the facet joint implant 10,more or fewer teeth, elongated fingers, and indents may be used. Inaddition, the arrangements of the teeth, elongated fingers, and indentsmay be altered. For example, the teeth and indents may be arranged toengage on adjacent sides of the elongated connector 70 rather than or inaddition to opposite lateral sides 75. Further, additional sets ofindents may be provided at additional locations to engage the teeth whenthe facet joint implant is in states of partial distal expansion ratherthan or in addition to the closed and open states described. The shapesof the teeth and indents may be varied. Still further, the teeth may beformed on other structures of the outer part 12 and the indents may beformed on other structures of the inner part 14. All of these variationscan be made without deviating from the concepts of the inventionprovided they are consistent with achieving the objectives describedherein.

4. First Delivery Device Interface and First (Outer) Connector.

The first delivery device interface 50 provides a connection interfaceto the outer part 12 of the facet joint implant 10 for a delivery device90 described below.

The first delivery device interface 50 is connected to the outer part 12of the facet joint implant 10. More specifically, the first deliverydevice interface 50 is connected to the first proximal end portion 22 ofthe first facet plate 20 and to the second proximal end portion 32 ofthe second facet plate 30. Still more specifically, the first deliverydevice interface 50 is connected to the proximal end portion 43 of theconnecting shoulder 41 and is connected via the connecting shoulder 41to the first proximal end portion 22 of the first facet plate 20 and tothe second proximal end portion 32 of the second facet plate 30.

Preferably, the connection of the first delivery device interface 50 tothe outer part 12 of the facet joint implant 10 is a substantially fixedor similar connection or attachment that does not allow the firstdelivery device interface 50 to substantially rotate or otherwise moverelative to the outer part 12. Rather, it is preferred that as the firstdelivery device interface 50 is moved, whether rotationally orotherwise, the outer part 12 of the facet joint implant 10 moves withit.

The first delivery device interface 50 of the facet joint implant 10comprises a first or outer connector 51. The first connector 51 isconfigured to be selectively engaged by a corresponding first connector100 of the delivery device 90 and to be brought into locking engagementwith the corresponding first connector 100 to hold the facet jointimplant 10 in a fixed orientation relative to the delivery device 90. Inthe example embodiments, the first connector 51 comprises a firstbayonet connector 52. The first bayonet connector 52 is adapted andconfigured to receive, engage, and be in locked engagement with a firstbayonet 101 of the corresponding first or outer connector 100 of thedelivery device 90 as described below.

The first or outer connector 51 comprises a substantially cylindricalbody 53 that defines an open interior space 54 with an open face 55. Thebody 53 has an exterior surface 56. The exterior surface 56 contains oneor more flats 57 adapted and configured to engage correspondingstructures of the delivery device 90 as described below.

The third opening 39 through the hinge 38 described previously alsoextends through the body of the connecting shoulder 41 and into the openinterior space 54 of the first connector 51. The third opening 39 isdimensioned and configured to allow the elongated connector 70 of theinner part 14 of the facet joint implant 10 to extend through the thirdopening 39 and to move distally and proximally relative to the hinge 38,connecting shoulder 41, and first connector 51 of the outer part 12 ofthe facet joint implant 10.

As described further below, a second or inner connector 81 of a seconddelivery device interface 80 connected to the inner part 14 of the facetjoint implant 10 is fixedly connected or attached to a proximal end ofthe elongated connector 70. As the second or inner connector 81 is movedin a distal direction toward the first facet plate 20 and the secondfacet plate 30 it enters the open interior space 54 of the first orouter connector 51 through the open face 55 and the first or outerconnector 51 extends around the second or inner connector 81. In theexample embodiments, the first or outer connector 51 and the second orinner connector 81 are arranged to be substantially concentric, althoughthat is a preference and not always necessary. As the second or innerconnector 81 is moved in a proximal direction away from the first facetplate 20 and the second facet plate 30, it exits the open interior space54 of the first or outer connector 51 through the open face 55 and isexposed outside the first or outer connector 51.

When the first connector 51 of the outer part 12 of the facet jointimplant 10 is in locked engagement with the corresponding firstconnector 100 of the delivery device 90, the facet joint implant 10 issecurely held in a fixed position and orientation relative to thedelivery device 90 and the position and orientation of the facet jointimplant 10 can be manipulated using the delivery device 90. Thisfacilitates the positioning and orientation of the facet joint implant10 for insertion into the body of a patient, delivery to a facet joint140 in which it is to be implanted, and implantation in the facet joint140.

Preferably, the first delivery device interface 50, more specificallythe first or outer connector 51, and even more specifically the firstbayonet connector 52 is configured to have an outer dimension greaterthan the expected or intended dimension of the posterior space betweenthe superior and inferior facets 143, 145 of the facet joint 140 inwhich the facet joint implant 10 is to be implanted, i.e., the dimensionof the expected or intended posterior opening 141 of the facet joint140. This facilitates the ability to achieve proper positioning of thefacet joint implant 10 in the facet joint 140 by allowing only thecomponents of the outer part 12 and the inner part 14 necessary todistally distract the facet joint 140 to be inserted and preventingover-insertion of the facet joint implant 10 in the joint. In addition,the distance or dimension between the first delivery device interface50, more specifically the first connector 51, and the distal end of thefacet joint implant 10 can vary based on the facet size and the intendedposition of the maximum expansion of the distal end of the facet jointimplant 10.

Preferably, the first delivery device interface 50, more specificallythe first or outer connector 51, and even more specifically the firstbayonet connector 52 is formed as a single monolithic structure with theother components of the outer part 12 of the facet joint implant 10.Alternatively, however, the first delivery device interface 50, morespecifically the first or outer connector 51, and even more specificallythe first bayonet connector 52 may be formed as a separate structure orstructures, and may be fixedly attached or connected with the othercomponents of the outer part 12 as described herein in any suitablemanner.

C. Inner Part.

Illustrated primarily in FIGS. 1A through 9E, the inner part 14 of thedistally expanding facet joint implant 10 comprises a wedge 61, a firstset of indents 73, a second set of indents 74, a second deliveryinterface 80 comprising a second or inner connector 81, and an elongatedconnector 70 between the wedge 61 and the second connector 81.

Preferably, the inner part 14 comprises a second monolithic structure,separate from the first monolithic structure of the outer part 12, inwhich all of the components of the inner part 14 are formed orfabricated together as a single structure. For example, the inner part14 may be formed or fabricated using a suitable 3D printing method suchas selective laser melting (SLM). Alternatively, suitable moldingtechniques can be employed. Also alternatively, one or more of thecomponents of the inner part 14 can be fabricated separately via SLM,other 3D printing techniques, and/or suitable molding or machiningprocesses, and can then be interconnected with the other components ofthe inner part 14 in any suitable manner.

Also preferably, the inner part 14 is formed at the same time as theouter part 12 described above, for example using a suitable 3D printingmethod such as SLM, and also is formed pre-assembled with the outer part12 as illustrated in FIGS. 1A through 8B for example. Alternatively, theinner part 14 may be fabricated separately from the outer part 12 andassembled with the outer part 12 as illustrated in the figures.

As described further below, the inner part 14 of the facet joint implant10 is moveable relative to the outer part 12. More specifically, theinner part 14 is movable in a distal direction toward the first facetplate 20 and the second facet plate 30, and in an opposite proximaldirection away from the first facet plate 20 and the second facet plate30. The movement of the inner part 14 relative to the outer part 12causes the facet joint implant 10 to distally expand and contractbetween the open and closed states depending on the direction of motionof the inner part 14. As previously mentioned, the inner part 14 is atleast partially exposed in the first opening 23 of the first facet plate20 and/or the second opening 33 of the second facet plate 30 tofacilitate controlling the movement of the inner part 14 relative to theouter part 12.

1. Wedge.

The inner part 14 includes an engagement structure 60 that is configuredand operable to be selectively moved relative to the outer part 12 andto engage the outer part 12 to selectively cause the facet joint implant10 to distally expand into the open state and distally contract into theclosed state. More specifically, the engagement structure is configuredand operable to be selectively moved in a distal direction toward andinto engagement with the first facet plate 20 and the second facet plate30 of the outer part 12 to selectively cause the first distal endportion 21 of the first facet plate 20 and the second distal end portion31 of the second facet plate 30 to expand apart to place the facet jointimplant 10 in the open state, and to be selectively moved in an oppositeproximal direction away from and out of engagement with the first facetplate 20 and the second facet plate 30 of the outer part 12 toselectively cause the first distal end portion 21 of the first facetplate 20 and the second distal end portion 31 of the second facet plate30 to contract toward each other and place the facet joint implant 10 inthe closed state.

Although the engagement structure 60 may take any shape suitable toaccomplish the above description, in the example embodiments, the innerpart 14 comprises a wedge 61 as the engagement structure 60. The wedge61 has a third distal end portion 62 and a third proximal end portion63. The third distal end portion 62 is adjacent to and faces the firstsloped portion 27 on the first interior surface 26 of the first facetplate 20 of the outer part 12 of the facet joint implant 10 and thesecond sloped portion 37 on the second interior surface 36 of the secondfacet plate 30 of the outer part 12 of the facet joint implant 10 whenthe facet joint implant 10 is in the closed state. The third proximalend portion 63 is connected to a distal end portion 71 of the elongatedconnector 70 of the inner part 14 and via the elongated connector 70 tothe second delivery device interface 80 of the inner part 14 describedbelow.

The wedge 61 also has a third exterior surface 64 and a fourth exteriorsurface 66. At least a portion of the third exterior surface 64 and aportion of the fourth exterior surface 66 are sloped. The sloped portionof the third exterior surface 64 comprises a third sloped portion 65 andthe sloped portion of the fourth exterior surface 66 comprises a fourthsloped portion 65.

Preferably, the third sloped portion 65 of the third exterior surface 64of the wedge 61 extends downwardly from the direction of the thirdproximal end portion 63 of the wedge 61 toward the third distal endportion 62 of the wedge 61. Preferably the fourth sloped portion 65 ofthe fourth exterior surface 66 of the wedge 61 extends downwardly fromthe direction of the third proximal end portion 63 of the wedge 61toward the third distal end portion 62 of the wedge 61. As a result, thethird distal end portion 62 of the wedge 61 has a first thickness andthe third proximal end portion 63 of the wedge 61 has a second thicknessgreater than the first thickness.

The third sloped portion 65 of the third exterior surface 64 of thewedge 61 is adapted to engage and to move relative to the first slopedportion 27 of the first interior surface 26 of the first facet plate 20of the outer part 12. The fourth sloped portion 65 of the fourthexterior surface 66 of the wedge 61 is adapted to engage and to moverelative to the second sloped portion 37 of the second interior surface36 of the second facet plate 30 of the outer part 12.

When the inner part 14 of the facet joint implant 10 is manipulatedusing the delivery device 90 and caused to move distally in thedirection of the first facet plate 20 and the second facet plate 30 ofthe outer part 12 of the facet joint implant 10 as described below, thedistally downward sloping third sloped portion 65 on the third exteriorsurface 64 of the wedge 61 engages and moves relative to the proximallyupward sloping first sloped portion 27 of the first interior surface 26of the first facet plate 20 of the outer part 12. Similarly, thedistally downward sloping fourth sloped portion 65 on the fourthexterior surface 66 of the wedge 61 engages and moves relative to theproximally upward sloping second sloped portion 37 of the secondinterior surface 36 of the second facet plate 30 of the outer part 12.

As the wedge 61 continues to move distally between the first facet plate20 and the second facet plate, the increasing thickness of the wedgebetween the first interior surface 26 of the first facet plate 20 andthe second interior surface 36 of the second facet plate 30 causes thefirst distal end portion 21 of the first facet plate 20 and the seconddistal end portion 31 of the second facet plate 30 to move and apartuntil the facet joint implant 10 reaches the distally expanded openposition. The first proximal end portion 22 of the first facet plate 20and the second proximal end portion 32 of the second facet plate 30rotate in a first set of opposite directions about the axis of the hinge38 and remain in close proximity as the facet joint implant 10 isdistally expanded, even when the facet joint implant 10 reaches the openposition.

Similarly, when the inner part 14 of the facet joint implant 10 ismanipulated using the delivery device 90 and caused to move proximallyin the opposite direction away from the first facet plate 20 and thesecond facet plate 30 of the outer part 12 of the facet joint implant10, the distally downward sloping third sloped portion 65 on the thirdexterior surface 64 of the wedge 61 moves relative to and in engagementwith the proximally upward sloping first sloped portion 27 of the firstinterior surface 26 of the first facet plate 20 of the outer part 12,and the distally downward sloping fourth sloped portion 65 on the fourthexterior surface 66 of the wedge 61 moves relative to and in engagementwith the proximally upward sloping second sloped portion 37 of thesecond interior surface 36 of the second facet plate 30 of the outerpart 12.

As the wedge 61 continues to move proximally between the first facetplate 20 and the second facet plate, the decreasing thickness of thewedge between the first interior surface 26 of the first facet plate 20and the second interior surface 36 of the second facet plate 30 causesthe first distal end portion 21 of the first facet plate 20 and thesecond distal end portion 31 of the second facet plate 30 to movetogether or toward each other until the facet joint implant 10 reachesthe distally contracted closed position. The first proximal end portion22 of the first facet plate 20 and the second proximal end portion 32 ofthe second facet plate 30 rotate in a second set of opposite directionsabout the axis of the hinge 38 and remain in close proximity as thefacet joint implant 10 is distally contracted and reaches the closedposition.

Preferably the wedge 61 also has substantially flat surfaces 68 on thethird exterior surface 64 between the third sloped portion 65 and thethird proximal end portion 63 of the wedge 61 and on the fourth exteriorsurface 66 between the fourth sloped portion 67 and the third proximalend portion 63 of the wedge 61. The flat surfaces 68 are configured tohelp distribute the pressure or weight exerted on the facet jointimplant 10 by the facet joint 140 over a wider surface area when thefacet joint implant 10 is positioned in the facet joint 140 with theexterior surfaces 24, 34 of the first and second facet plates 20, 30 incontact with the interior facet surfaces 150, 152.

Preferably, the engagement structure 60 and more specifically the wedge61 is formed as a single monolithic structure with the other componentsof the inner part 14 of the facet joint implant 10. Alternatively,however, the engagement structure 60 and more specifically the wedge 61may be formed as a separate structure or structures, and may be fixedlyattached or connected with the other components of the inner part 14 asdescribed herein in any suitable manner.

2. Indents.

As described above, the inner part 14 of the facet joint implant 10comprises a first set of indents 73, wherein the first set of indents 73is located on the inner part 14 so that when the facet joint implant 10is in the closed state, the first set of teeth 40 of the outer part 12of the facet joint implant 10 is engaged with the first set of indents73. Similarly, the inner part 14 of the facet joint implant 10 comprisesa second set of indents 74, wherein the second set of indents 74 islocated on the inner part 14 so that when the facet joint implant 10 isin the open state, the first set of teeth of the outer part 12 isengaged with the second set of indents 74.

More specifically, and as described above, in the example embodimentsthe first set of indents 73 and the second set of indents 74 are formedin the surfaces of opposite lateral sides 75 of the elongated connector70 of the inner part 14 of the facet joint implant 10 with the oppositelateral sides 75 facing corresponding teeth of a first set of teeth 40formed on the outer part 12 of the facet joint implant 10. The first setof indents 73 and the second set of indents 74 are configured, arerelatively positioned, and are operable to function like a ratchet withthe first set of teeth 40 to help hold the inner part 14 of the facetjoint implant 10 in one of two selected positions relative to the outerpart 12 of the facet joint implant 10, and hence the facet joint implant10 in one of two selected states or positions of distal expansion.

In the example embodiments, these two selected positions correspond tothe closed state and the open state of the facet joint implant 10respectively. Thus, the first set of indents 73 is formed on oppositelateral sides 75 of the elongated connector 70 at the distal end portion71 of the elongated connector 70 at a first position that is justproximal to the third proximal end portion 63 of the wedge 61. At thisfirst position, the first set of indents 73 align with the first set ofteeth 40 of the outer part 12 of the facet joint implant 10 when theelongated connector 70 is positioned such that the third distal endportion 62 of the wedge 61 is adjacent to but not substantially engagedwith the first interior surface 26 of the first facet plate 20 of theouter part 12 and the second interior surface 36 of the second facetplate 30 of the outer part 12. This corresponds to the distallycontracted closed state of the facet joint implant 10.

Similarly, the second set of indents 74 is formed on the same oppositelateral sides 75 of the elongated connector 70 as the first set ofindents 73 but at a second position that is spaced apart from the firstposition and is closer to the proximal end of the elongated connector 70to which the second delivery device interface 80 is connected. At thissecond position, the second set of indents 74 aligns with the first setof teeth 40 of the outer part 12 when the wedge 61 is fully insertedbetween the first facet plate 20 and the second facet plate 30 with thethird exterior surface 64 of the wedge 61 and the fourth interiorsurface 65 of the wedge engaged with the first interior surface 26 ofthe first facet plate 20 and the second interior surface 36 of thesecond facet plate 30 respectively. This corresponds to the distallyexpanded open state of the facet joint implant 10.

As described previously, the first set of indents 73 and the second setof indents 74 are preferably configured and dimensioned to facilitatethe first set of teeth 40 securely engaging and seating in the indentsto securely (but not irreversibly) hold the inner part 14 of the facetjoint implant 10 in position relative to the outer part 12 of the facetjoint implant 10. As mentioned above, it also is preferred that theindents be configured to provide a physical feedback, such as a clickingfeel or sound, when the first set of teeth 40 engage and seat in thefirst set of indents 73 and the second set of indents 74.

The secure engagement and seating of the first set of teeth 40 in theindents is particularly beneficial when the facet joint implant 10 isdeployed in a facet joint 140 in the distally expanded open state forthe reasons explained above. As also described above, it is preferredthat at least the second set of indents 74 are configured anddimensioned so that the force with which they engage and hold the firstset of teeth 40 is sufficient to reliably keep the facet joint 140distracted anteriorly. At the same time, the holding force may or maynot be so great as to prevent an operator from manually disengaging thefirst set of teeth 40 from the second set of indents 74, and manuallycausing the facet joint implant 10 to distally contract. For example, ifit is deemed desirable or necessary to be able to reposition the facetjoint implant 10 in the facet joint 140 or to remove it from the facetjoint 140 once it has been distally expanded, the second set of indents74 can be configured to permit the first set of teeth 140 to be manuallydisengaged from the second set of indents 74 by the application of adegree of force so that the facet joint implant 10 can be manuallydistally contracted. Alternatively, however, the indents 74 and teeth 40can be made deeper or can be otherwise configured to substantiallyprevent the first set of teeth 40 from being disengaged, and thussubstantially prevent the facet joint implant 10 from being distallycontracted once it has been distally expanded to the open state.

It is preferred that the first set of indents 73 and second set ofindents 74 be at least partially visible through the first opening 23 inthe first facet plate 20 and/or the second opening 33 in the secondfacet plate 30. This facilitates observation of the movement of theinner part 14 of the facet joint implant 10 relative to the outer part12 of the facet joint implant 10, for example to confirm properoperation of the facet joint implant 10 prior to insertion anddeployment.

It is also preferred that the first set of indents 73, the second set ofindents 74, and the elongated connector 70 be formed as a singlemonolithic structure with each other and with the other components ofthe inner part 14 of the facet joint implant 10. Alternatively, however,the components may be formed as one or more separate structures, and canbe attached or connected together and with the other components of theinner part 14 in any suitable manner.

In the specific example embodiments illustrated, the first set ofindents 73 and the second set of indents 74 each comprise two indentslocated on opposite lateral sides of the elongated connector 70.However, persons skilled in the art will appreciate that depending onparticular circumstances and intended applications of the facet jointimplant 10, more or fewer indents may be used in each set and total. Inaddition, the arrangements of the indents may be altered. For example,indents may be arranged on adjacent sides of the elongated connector 70rather than or in addition to opposite lateral sides 75. Further,additional sets of indents may be provided at additional locations toengage teeth of the outer part 12 when the facet joint implant is instates of partial distal expansion rather than or in addition to theclosed and open states as described. The corresponding shapes of theindents and teeth may be varied. Still further, the indents may beformed on other structures of the inner part 14 rather than or inaddition to the elongated connector 70. All of these variations can bemade without deviating from the concepts of the invention provided theyare consistent with achieving the objectives described herein.

3. Second Delivery Device Interface and Second (Inner) Connector.

The second delivery device interface 80 provides a connection interfaceto the inner part 14 of the facet joint implant 10 for the deliverydevice 90 described below.

The second delivery device interface 80 is connected to the inner part14 of the facet joint implant 10. More specifically, the second deliverydevice interface 80 is connected to the wedge 61. Still morespecifically, the second delivery device interface is connected to thethird proximal end portion 63 of the wedge 61. Even more specifically,the second delivery device interface 80 is connected to the proximal endportion 72 of the elongated connector 70 and is connected via theelongated connector 70 to the third proximal end portion 63 of the wedge61.

Preferably, the connection of the second delivery device interface 80 tothe inner part 14 of the facet joint implant 10 is a substantially fixedor similar connection or attachment that does not allow the seconddelivery device interface 80 to substantially move relative to the innerpart 14. Rather, it is preferred that as the second delivery deviceinterface 80 is moved, the inner part 14 of the facet joint implant 10moves with it relative to the outer part 12 of the facet joint implant10.

The second delivery device interface 80 of the facet joint implant 10comprises a second or inner connector 81. The second connector 81 isconfigured to be selectively engaged by and to be brought into lockedengagement with a corresponding second connector 110 of the deliverydevice 90 to impart motion to the inner part 14 of the facet jointimplant 10 relative to the outer part 12 of the facet joint implant 10.The second connector 81 is configured to be engaged by the correspondingsecond connector 110 by receiving the corresponding second connector 110at least partially in the second connector 81. The second connector 81is configured to be brought into locked engagement with thecorresponding second connector 110 by permitting the correspondingsecond connector 110 to rotate within and relative to the secondconnector 81, for example by approximately 90 degrees.

In the example embodiments, the second connector 81 comprises a secondbayonet connector 82. The second bayonet connector 82 is adapted andconfigured to receive, be engaged by, and be brought into lockedengagement with a second bayonet 111 of the corresponding secondconnector 110 of the delivery device 90, which is described furtherbelow. The second bayonet connector 82 comprises a substantiallycylindrical body 83 that defines an open interior space 84 with an openface 85 for receiving a second bayonet 111 of the corresponding secondconnector 110 of the delivery device 90. The open face 85 is shaped andadapted to permit the second bayonet 111 to be inserted into the openinterior space 84 of the second bayonet connector 82 and to be broughtinto engagement with the second bayonet connector 82. The second bayonetconnector 82 is further adapted and configured to be brought into lockedengagement with the second bayonet 111 of the delivery device 90 bypermitting the second bayonet 111 to rotate within and relative to thesecond bayonet connector 82, for example by approximately 90 degrees.

The shape of the open face 85 is adapted both to act as a key openingfor a second key 113 of the delivery device 90 as described furtherbelow, and more importantly to prevent the second bayonet 111 frominadvertently exiting the second bayonet connector 82 once it is inlocked engagement. Thus, the open face 85 is shaped to only allow thesecond bayonet 111 to be inserted in or to be withdrawn from the secondbayonet connector 82 when the second bayonet 111 is in a particularorientation relative to the second bayonet connector 82. Conversely, theopen face 85 is shaped and adapted to block the second bayonet 111 frombeing inserted into or withdrawn from the open interior space 84 of thesecond bayonet connector 82 when the second bayonet 111 is not in theparticular orientation relative to the second bayonet connector 82.

As described above, as the second or inner connector 81 is moved in adistal direction toward the first facet plate 20 and the second facetplate 30 of the outer part 12 of the facet joint implant 10, the secondconnector 81 enters the open interior space 54 of the first or outerconnector 51 of the outer part 12 through the open face 55 and the firstor outer connector 51 extends around the second or inner connector 81.In the example embodiments, the first or outer connector 51 and thesecond or inner connector 81 are arranged to be substantiallyconcentric, although that is a preference and is not always necessary.As the second or inner connector 81 is moved in a proximal directionaway from the first facet plate 20 and the second facet plate 30, itexits the open interior space 54 of the first or outer connector 51through the open face 55 and is exposed outside the first or outerconnector 51.

As described previously, the third opening 39 through the hinge 38 ofthe outer part 12 of the facet joint implant 10 also extends through thebody of the connecting shoulder 41 of the outer part 12 and into theopen interior space 54 of the first connector 51 of the outer part 12.The elongated connector 70 of the inner part 14 extends through thethird opening 39 and is movable within the third opening 39 in distaland proximal directions relative to the outer part 12 of the facet jointimplant 10. Preferably, the second or inner connector 81, morespecifically the second bayonet connector 82, and even more specificallythe body 83 of the second bayonet connector 82, is configured anddimensioned relative to the third opening 39 so that the secondconnector 81 cannot enter the third opening 39 through the first orouter connector 51.

Because the second or inner connector 81 is fixedly connected to theelongated connector 70, when the second connector 81 is moved in adistal direction toward the first facet plate 20 and the second facetplate 30 of the outer part 12, so is the elongated connector 70.Similarly, when the second or inner connector 81 is moved in an oppositeproximal direction away from the first facet plate 20 and the secondfacet plate 30 of the outer part 12, so is the elongated connector 70.Thus, moving the second or inner connector 81 also moves the inner part14 of the facet joint implant 10 relative to the outer part 12 of thefacet joint implant 10.

Accordingly, because the wedge 61 is connected at the distal end portion71 of the elongated connector 70, moving the second or inner connector81 in the distal direction toward the first facet plate 20 and thesecond facet plate 30 of the outer part 12 causes the wedge 61 to engageand move relative to the first facet plate 20 and the second facet plate30, which in turn causes the facet joint implant 10 to distally expandto the open state in the manner previously described. Similarly, movingthe second or inner connector 81 in the opposite proximal direction awayfrom the first facet plate 20 and the second facet plate 30 of the outerpart 12 causes the wedge 61 to move relative to and to disengage fromthe first facet plate 20 and the second facet plate 30, which in turncauses the facet joint implant 10 to distally contract to the closedstate in the manner previously described.

When the second connector 81 of the inner part 14 of the facet jointimplant 10 is in engagement with but not necessarily in lockedengagement with the corresponding second connector 110 of the deliverydevice 90, the delivery device 90 can be manipulated as described belowto selectively cause the second connector 81 and the inner part 14 ofthe facet joint implant 10, including the wedge 61, to move distallyrelative to the outer part 12, including the first facet plate 20 andthe second facet plate 30. Thus, the delivery device 90 can bemanipulated to selectively cause the facet joint implant 10 to distallyexpand from its closed state to its open state. This is possible becausethe wedge 61 is pushed in a distal direction, rather than pulled in aproximal direction, to cause the facet joint implant 10 to distallyexpand to the open state. When the second connector 81 is in lockedengagement with the corresponding second connector 110, the deliverydevice 90 also can be manipulated as described below to selectivelycause the second connector 81 and the wedge 61 to move proximallyrelative to the first facet plate 20 and the second facet plate 30.Thus, the delivery device 90 also can be manipulated to selectivelycause the facet joint implant 10 to distally contract from the openstate to the closed state in the manner described herein.

In the example embodiments illustrated in FIGS. 1A through 9B, thesecond delivery device interface 80, more specifically the second orinner connector 81, and even more specifically the second bayonetconnector 82 is preferably formed as a single monolithic structure withthe other components of the inner part 14 of the facet joint implant 10.Alternatively, however, the second delivery device interface 80, morespecifically the second or inner connector 81, and even morespecifically the second bayonet connector 82 may be formed as a separatestructure or structures, and may be fixedly and rigidly attached orconnected with the other components of the inner part 14 as describedherein in any suitable manner.

In an alternative example embodiment illustrated in FIGS. 9C-9E, thesecond delivery device interface 80, more specifically the second orinner connector 81, and even more specifically the second bayonetconnector 82 is formed as a separate structure from the remainingcomponents of the inner part 14 of the facet joint implant 10. In thealternative embodiment, the second delivery device interface 80, morespecifically the second or inner connector 81, and even morespecifically the second bayonet connector 82 is connected to theelongated connector 70 of the inner part 14 by a ball-socket connector86.

As described further below, the ball-socket connector 86 enables thesecond bayonet connector 82 to be rotated relative to and withoutrotating the elongated connector 70 or the wedge 61 of the inner part 14of the facet joint implant 10 and to cause the inner part 14 totranslate in distal and proximal directions relative to the outer part12 of the facet joint implant 10 without rotating. The ball-socketconnector 86 can also be replaced by a disc-in-socket connector or anyother connector that permits the second connector 81 to be rotated atthe proximal end portion of the facet joint implant 10 and to cause theinner part 14 to be pushed in the direction of the distal end portion ofthe facet joint implant 10 or to be pulled in the direction of theproximal end portion relative to the outer part 12 without rotating theother components of the inner part 14 nearer the distal end portion ofthe facet joint implant 10.

The ball-socket connector 86 comprises a ball 87. The ball 87 is seatedin a socket 88 formed in the body 83 of the second connector 81. Thesocket 88 and hence the body 83 of the second connector 81 is able torotate on and relative to the ball 87.

The ball-socket connector 86 and hence the second connector 81 ispreferably rigidly but removably coupled to the elongated connector 70of the inner part 14 of the facet joint implant 10. This coupling may beaccomplished in many suitable ways. In one preferred way, theball-socket connector 86 comprises a threaded shaft 89 having outsidethreads. The threaded shaft 89 is fixedly connected or attached to theball 87 and extends outwardly from the socket 88.

The proximal end 72 of the elongated connector 70 of the inner part 14of the facet joint implant 10 comprises a threaded passage 76 havinginner threads. The threaded shaft 89 of the ball-socket connector 86extends within the threaded passage 76 of the elongated connector 70with the outer threads of the threaded shaft 89 in threaded engagementwith the inner threads of the threaded passage 76. With the ball-socket86 coupled to the elongated connector 70, the socket 88 and hence thesecond connector 81 is free to rotate on the ball 87 relative to theelongated connector 70. The second connector 81 is also free to rotaterelative to the first or outer connector 51 of the outer part 12 of thefacet joint implant.

The body 83 of the second or inner connector 81 is provided with a setof outer threads 83A. The body 53 of the first or outer connector 51 isprovided with a corresponding set of inner threads 53A. The body 83 ofthe second or inner connector 81 and the body 53 of the first or outerconnector 51 are dimensioned and configured so that when the second orinner connector 81 is positioned within the first or outer connector 51,for example as illustrated in FIG. 1B, the outer threads 83A on the body83 of the second or inner connector 81 engage with the inner threads 53Aon the body 53 of the first or outer connector 51.

When the first connector 51 is in locked engagement with thecorresponding first connector 100 of the delivery device 90 as describedherein, the outer part 12 of the facet joint implant 10 is held inposition by the delivery device 90 and the inner part 14 of the facetjoint implant 10 is free to move relative to the outer part 12.Accordingly, rotation of the second connector 81 within the firstconnector 51 causes the second connector 81 to translate within thefirst connector 51 on the inner and outer threads 53A, 83A. This in turncauses the inner part 14, including the wedge 61, to advance distally orretract proximally relative to the outer part 12, including the firstfacet plate 20 and the second facet plate 30, depending on whichdirection the second connector 81 is rotated. In turn, this causes thefacet joint implant 10 to distally expand or to distally contract in themanner described herein, again depending on the direction the secondconnector 81 is rotated.

As an additional alternative, the entire inner part 14 could simply bereplaced by a threaded screw with outer threads, and the entire outerpart 12 could simply be replaced by a structure with a thicker distalend than proximal end and a passage with inner threads. In thisalternative, the threaded screw would extend into the passage with theouter threads of the screw engaged with the inner threads of thepassage. Rotation of the screw relative to passage would cause thethicker distal end of the structure to translate distally creating awedge-like expansion of the facet joint implant.

D. Delivery Device.

Illustrated primarily in FIGS. 10 through 26D, the delivery device 90for use with the distally expanding facet joint implant 10 is anelongated device with a distal end portion 92 and a proximal end portion93. The delivery device 90 generally comprises a hollow outer tube 91that extends between the distal end portion 92 and the proximal endportion 93. The delivery device 90 also comprises a hollow inner tube105 that extends between the distal end portion 92 and the proximal endportion 93 and that has a corresponding first or outer connector 100 atthe distal end portion 92. The corresponding first or outer connector100 is configured to be brought into engagement and into lockedengagement with the first or outer connector 51 of the first deliverydevice interface 50 of the facet joint implant 10. The delivery device90 also comprises an inner shaft 115 that extends between the distal endportion 92 and the proximal end portion 93 and that has a correspondingsecond or inner connector 110 at the distal end portion 92. Thecorresponding second or inner connector 110 is configured to be broughtinto engagement and into locked engagement with the second or innerconnector 81 of the second delivery device interface 80 of the facetjoint implant 10.

The delivery device 90 also comprises an outer tube control knob 116that is located at the proximal end portion 93 and that is coupled withthe outer tube 91 and with the inner tube 105. The delivery device 90also comprises a control handle 120 that is located at the proximal endportion 93 and that is coupled with the corresponding first connector100 via the inner tube 105. The delivery device 90 further comprises aninner shaft control knob 121 that is located at the proximal end portion93 and that is coupled with the corresponding second connector 110 ofthe delivery device 90 via the inner shaft 115. The delivery device 90further comprises a lock switch 124 and lock 162 that are located at theproximal end portion 93 and that are coupled with the correspondingsecond connector 110 of the delivery device 90 via the inner shaft 115.

The delivery device 90 is used to introduce the facet joint implant 10into the body of a patient posteriorly through a posterior incision andto deliver the facet joint implant 10 through a preferably dilatedpassageway to a facet joint 140 in which the facet joint implant 10 isto be implanted. Once the facet joint implant 10 is at the facet joint140, the delivery device 90 is used to position and orient the facetjoint implant 10 relative to a posterior opening 141 of the facet joint140 as desired, and then to insert the facet joint implant 10 into thefacet joint 140, position the facet joint implant 10 in the facet joint140 as desired, and deploy the facet joint implant 10 by causing it todistally expand to its open position to distally distract the facetjoint 140. The delivery device 90 may also be used to cause the facetjoint implant 10 to distally contract to its closed position forrepositioning within the facet joint 140 or even removal from the facetjoint 140.

1. Corresponding First (Outer) Connector.

The corresponding first or outer connector 100 is located at the distalend of the hollow inner tube 105 at the distal end portion 92 of thedelivery device 90. The corresponding first or outer connector 100 isconfigured to selectively be brought into engagement with the first orouter connector 51 of the first delivery device interface 50 of thefacet joint implant 10 and to selectively be inserted into the first orouter connector 51. The corresponding first or outer connector 100 isalso configured to selectively be brought into locked engagement withthe first or outer connector 51 to hold the facet joint implant 10 in afixed position and orientation relative to the delivery device 90. Thisenables the delivery device 90 to be manipulated to insert the facetjoint implant 10 into the body of a patient, deliver it to a facet joint140 in which it is to be implanted, insert it in the facet joint 140,and position it within the facet joint 140.

The hollow inner tube 105 and the corresponding first connector 100 areat least partially contained within the hollow outer tube 91 and aremovable relative to the hollow outer tube 91 for the corresponding firstconnector 100 to be selectively brought into engagement with andinserted into the first connector 51 of the first delivery deviceinterface 50 of the facet joint implant 10, and for the correspondingfirst connector 100 to be selectively brought into locked engagementwith the first connector 51. More specifically, the hollow inner tube105 and the corresponding first connector 100 are at least rotationallymovable within and relative to the hollow outer tube 91. At least aportion of the corresponding first connector 100 extends beyond thedistal end portion 92 of the hollow outer tube 91 and is exposed outsideof the hollow outer tube 91 for being brought into engagement, beinginserted in, and being brought into locked engagement with the firstconnector 51 of the first delivery device interface 50 of the facetjoint implant 10. In the example embodiments, the corresponding first orouter connector 100 of the delivery device 90 and the first or outerconnector 51 of the facet joint implant 10 are brought into engagementby manipulating the delivery device 90 to bring the corresponding firstconnector 100 into contact with the first connector 51 in the properalignment. When the corresponding first connector 100 is in properalignment with the first connector, the delivery device 90 ismanipulated to insert the corresponding first connector 100 at leastpartially in the first connector 51. Once the corresponding firstconnector 100 is inserted in the first connector 51, the correspondingfirst connector 100 is brought into locked engagement with the firstconnector 51 by rotating the corresponding first connector 100 withinthe first connector 51, for example by approximately 90 degrees. This isaccomplished in a manner described further below.

Although the corresponding first connector 100 can take many suitableforms, in the example embodiments where the first or outer connector 51of the facet joint implant 10 comprises a first bayonet connector 52,the corresponding first connector 100 of the delivery device 90comprises a first bayonet 101. Preferably, the first bayonet 101 has asubstantially cylindrical shape and is configured and dimensioned to beat least partially insertable into the interior space 54 of the body 53of the first bayonet connector 52 through the open face 55. Preferably,the first bayonet 101 is configured and dimensioned so that rotating itrelative to the body 53 of the first bayonet connector 52 by 90 degrees,for example, locks it in engagement with first bayonet connector 52.

The hollow outer tube 91 of the delivery device 90 is provided with afirst key 94 to ensure the corresponding first or outer connector 100 ofthe delivery device 90 can only be brought into engagement with andinserted in the first or outer connector 51 of the outer part 12 of thefacet joint implant 10 in proper alignment. The first key 94 alsoprevents the facet joint implant 10 from inadvertently rotating relativeto the delivery device 90 when it is connected to the delivery device90.

The first key 94 comprises a set of holding arms 95. The holding arms 95extend outwardly from the distal end portion 92 of the hollow outer tube91 of the delivery device 90 around the exterior of the correspondingfirst connector 100. In the example embodiments, two holding arms 95extend from the distal end portion 92 of the hollow outer tube 91 onopposite sides of the corresponding first connector 100. Each holdingarm 95 has a flat portion 96 that faces the corresponding firstconnector 100.

The holding arms 95 and flat portions 96 are configured so that thecorresponding first connector 100 of the delivery device 90 can only bebrought into engagement with and inserted into the first connector 51 ofthe facet joint implant 10 when the flat portions 96 on the holding arms95 are aligned with the flats 57 on the exterior surface 56 of the body53 of the first connector 51. When the flat portions 96 on the holdingarms 95 are aligned with the flats 57 on the exterior surface 56 of thebody 53 of the first connector 51 and it is attempted to insert thecorresponding first connector 100 in the first connector 51, the flatportions 96 of the holding arms 95 pass outside of and over the flats109 on the exterior surface 56 of the body 53 of the first connector 51permitting the corresponding first connector 100 to be inserted in thefirst connector 51. If the flat portions 96 on the holding arms 95 arenot aligned with the flats 57 on the exterior surface 56 of the body 53of the first connector 51 when it is attempted to bring thecorresponding first connector 100 into engagement with first connector51 and to insert the corresponding first connector 100 in the firstconnector 51, the flat portions 96 on the holding arms 95 make contactwith the body 53 of the first connector 51 and the corresponding firstconnector 100 is blocked from being inserted.

When the corresponding first connector 100 is brought into engagementwith the first connector 51 and is inserted in the first connector 51with the proper alignment, i.e., with the flat portions 96 on theholding arms 95 aligned with the flats 57 on the exterior surface 56 ofthe body 53 of the first connector 51, the holding arms 95 also preventthe body 53 of the first connector 51 from rotating relative to theholding arms 95. Hence, the first connector 51 is prevented fromrotating relative to the corresponding first connector 100 and the outerpart 12 of the facet joint implant 10 is prevented from rotatingrelative to the delivery device 90.

Each of the holding arms 95 also includes a support surface 97. Thesupport surfaces 97 are located adjacent to the flat portions 96, aresubstantially flat, and are approximately perpendicular to the flatportions 96. The support surfaces 97 are configured to be engaged bysurfaces of the body 53 of the first connector 51 when the correspondingfirst connector 100 is inserted in the first connector 51, thecorresponding first connector 100 and the first connector 51 are broughtinto locked engagement, and the flat portions 96 of the holding arms 95are advanced over the flats 57 on the body 53 of the first connector 51.The engagement of the body 53 of the first connector 51 with the supportsurfaces 97 further stabilizes the connection between the facet jointimplant 10 and the delivery device 90. The holding arms 95, includingthe flat portions 96 and support surfaces 97, are configured to beadvanced and withdrawn relative to the corresponding first connector 100and the first connector 51 using the outer tube control knob 116 of thedelivery device 90 in a manner described further below.

When it is desired to connect the facet joint implant 10 to the distalend portion 92 of the delivery device 90 for introduction into the bodyof a patient, for example, the corresponding first or outer connector100 of the delivery device 90, and more specifically the first bayonet101, is aligned with the first or outer connector 51 of the facet jointimplant 10, and more specifically the first bayonet connector 52. Thecorresponding first or outer connector 100 of the delivery device 90,and more specifically the first bayonet 101, is then brought intoengagement with the first or outer connector 51, and more specificallythe first bayonet connector 52, of the outer part 12 of the facet jointimplant 10, and the corresponding first connector 100, and morespecifically the first bayonet 101, is inserted into the first connector51 and more specifically the first bayonet connector 52.

The corresponding first or outer connector 100 of the delivery device90, and more specifically the first bayonet 101, is then rotatedrelative to the first or outer connector 51 of the outer part 12 of thefacet joint implant 10, and more specifically the first bayonetconnector 52, to bring the corresponding first connector 100 and thefirst connector 51 into locked engagement. The corresponding firstconnector 100 of the delivery device 90 is rotated relative to the firstconnector 51 of the facet joint implant 10 using the control handle 120as described below.

The flat portions 96 on the holding arms 95 of the delivery device arealigned with the flats 57 on the body 53 of the first connector 51 bymanipulating the outer tube 91 of the delivery device 90, which isdescribed further below. The connection between the facet joint implant10 and the delivery device 90 is further stabilized by using the outertube control knob 116 of the delivery device 90 to advance the holdingarms 95 of the delivery device 90 around the body 53 of the firstconnector 51 so that the body 53 of the first connector 51 is broughtinto engagement with the support surfaces 97 of the holding arms 95,also as described below.

With the corresponding first or outer connector 100 of the deliverydevice 90 and the first or outer connector 51 of the facet joint implant10 in locked engagement, the facet joint implant 10 is securely held ina fixed position and orientation relative to the delivery device 90. Thedelivery device 90 can then be manipulated to introduce the facet jointimplant 10 into the body of a patient and to deliver it to and insert itin the facet joint 140 in which it is to be implanted. When it isdesired to disconnect the delivery device 90 from the facet jointimplant 10, the process is simply reversed. The holding arms 95 of thedelivery device 90 are retracted relative to the first correspondingconnector 100 of the delivery device 90 and the first connector 51 ofthe facet joint implant 10. Then the corresponding first connector 100,and more specifically the first bayonet 101, is rotated in the oppositedirection and is withdrawn from the first connector 51, and morespecifically the first bayonet connector 52, of the facet joint implant10.

In the example embodiments, the corresponding first connector 100 of thedelivery device 90 is preferably substantially cylindrical in shape. Inaddition, the corresponding first connector 100 is preferably at leastpartially hollow with an interior space 102 and the corresponding secondor inner connector 110 of the delivery device 90 is at least partiallycontained within the interior space 102 of corresponding first connector100. The corresponding second or inner connector 110 of the deliverydevice 90 is described further below. In the example embodiments, thecorresponding second or inner connector 110 is also substantiallycylindrical in shape, and the corresponding first connector 100 and thecorresponding second connector 110 are arranged to be substantiallyconcentric. However, that arrangement is a matter of preference and isnot always necessary.

The corresponding first connector 100 also has an open face 103 at thedistal end portion 92 of the delivery device 90 and the open face 103provides access to the interior space 102 within the corresponding firstconnector 100. The corresponding first connector 100 is configured anddimensioned so that when it is properly inserted in the first or outerconnector 51 of the facet joint implant 10, the second or innerconnector 81 of the facet joint implant 10 extends at least partiallythrough the open face 103 and into the interior space 102 of thecorresponding first connector 100 where it can be brought intoengagement with, inserted in, and brought into locked engagement withthe corresponding second connector 110 of the delivery device 90 asdescribed below.

The inner tube 105 of the delivery device 90 has an opening comprising awindow 104. The window 104 is located at the distal end portion 92 ofthe delivery device 90 and is spaced just proximally from thecorresponding first connector 100. The window 104 is located so thatwhen the corresponding first connector 100 is brought into engagementwith and is inserted in the first connector 51 of the facet jointimplant 10, the second or inner connector 82 of the facet joint implant10 is at least partially visible through the window 104. In addition,the corresponding second connector 110 of the delivery device 90 also isat least partially visible through the window 104 when it is broughtinto engagement with the second connector 81. This facilitates checkingthe orientation of the corresponding second connector 110 relative tothe second connector 81 and if necessary adjusting the alignment so thatthe corresponding second connector 110 can be brought into engagementwith, inserted into, and brought into locked engagement with the secondconnector 81 as described further below.

The corresponding first connector 100 is formed or connected at thedistal end of the inner tube 105. The inner tube 105 extends within thehollow outer tube 91 from the distal end portion 92 of the deliverydevice 90 to the proximal end portion 93 of the delivery device 90. Theinner tube 105 is moveable within and relative to the hollow outer tube91, and more specifically is rotationally moveable within and relativeto the hollow outer tube 91.

In the example embodiments, the inner tube 105 is substantiallycylindrical shaped and is at least partially hollow. The correspondingsecond connector 110 of the delivery device is formed or connected tothe distal end of the inner shaft 115, which extends within the hollowouter tube 91, and more specifically within the hollow inner tube 105within the hollow outer tube 91, from the corresponding second connector110 at the distal end portion 92 of the delivery device 90 to theproximal end portion 93 of the delivery device 90. Preferably but notnecessarily, the hollow inner tube 105 and the inner shaft 115 arearranged to be substantially concentric. The corresponding secondconnector 110 and the inner shaft 115 are described further below.

At the proximal end portion 93 of the delivery device 90, the outer tube91 is fixedly connected or attached to the outer tube control knob 116,which is in turn rotatably connected to the inner tube 105 in a mannerdescribed further below. The inner tube 105 also is fixedly connected orattached to the control handle 120 of the delivery device 90. The outertube 91 is configured and adapted to be controlled by the outer tubecontrol knob 116. More specifically, movement of the outer tube 91 toadvance and withdraw relative to the inner tube 105 and thecorresponding first connector 100 is controllable via manipulation ofthe outer tube control knob 116. The inner tube 105 and thecorresponding first connector 100 are configured and adapted to becontrolled by the control handle 120. More specifically, the movement ofthe inner tube 105 and the movement of the corresponding first connector100 are controllable via manipulation of the control handle 120. Theoperation of the outer tube control knob 116 and the control handle 120are described further below.

It is preferred that the corresponding first connector 100 and the innertube 105 comprise a single monolithic structure. However, the inner tube105 can comprise a separate structure from the corresponding firstconnector 100. In that case, the corresponding first connector 100 ispreferably fixedly connected or attached to the inner tube 105 at thedistal end of the delivery device 90 so that the inner tube 105 and thecorresponding first connector 100 move together, e.g., when the innertube 105 is rotated within the hollow outer tube 91, the correspondingfirst connector 100 rotates the same.

2. Corresponding Second (Inner) Connector.

The corresponding second or inner connector 110 is located at the distalend of the inner shaft 115 at the distal end portion 92 of the deliverydevice 90. The corresponding second connector 110 is configured andoperable to selectively be brought into engagement with the second orinner connector 81 of the first delivery interface 80 of the facet jointimplant 10 and to be selectively inserted into the second or innerconnector 81. The corresponding second connector 100 also is configuredand operable to selectively be brought into locked engagement with thesecond or inner connector 81. The corresponding second connector 110also is configured and operable to impart motion to the inner part 14 ofthe facet joint implant 10 relative to the outer part 12 of the facetjoint implant 10. The delivery device 90 is thus able to be manipulatedto cause the facet joint implant 10 to distally expand to its openposition in a facet joint 140 in which it is implanted so as to distallydistract the facet joint 140, and to cause the facet joint implant 10 todistally retract in order to reposition or remove the facet jointimplant 10 from the facet joint 140.

More specifically, the inner shaft 115 and the corresponding secondconnector 110 are at least partially contained within the hollow outertube 91 and are movable relative to the hollow outer tube 91 toselectively be brought into engagement with, inserted into, and broughtinto locked engagement with the second connector 81 to impart motion tothe wedge 61 of the inner part 14 of the facet joint implant 10 relativeto the first facet plate 20 and the second facet plate 30 of the outerpart 12 of the facet joint implant 10. Still more specifically, theinner shaft 115 and the corresponding second connector 110 areselectively moveable at least in the direction of the distal end portion92 and the proximal end portion 93 of the delivery device 90,rotationally within and relative to the hollow outer tube 91, andrelative to the corresponding first connector 100. Even morespecifically, the inner shaft 115 and the corresponding second connector110 are at least partially contained within the hollow inner tube 105within the hollow outer tube 91 of the delivery device 90, and areselectively movable at least in the direction of the distal end portion92 and the proximal end portion 93 of the delivery device 90 androtationally within and relative to the hollow inner tube 105 within thehollow outer tube 91, and relative to the corresponding first connector100.

As mentioned previously, in the example embodiments the inner shaft 115and the corresponding second connector 110 are substantially cylindricalin shape and are at least partially contained within the substantiallycylindrical shaped and at least partially hollow inner tube 105. Inaddition, the hollow inner tube 105 and the corresponding firstconnector 100, and the inner shaft 115 and the corresponding secondconnector 110 preferably are arranged to be substantially concentric.However, this arrangement is a matter of preference and not necessity.

In the example embodiments, the corresponding second or inner connector110 of the delivery device 90 and the second or inner connector 81 ofthe facet joint implant 10 are brought into engagement by manipulatingthe delivery device 90 to bring the corresponding second connector 110into contact with the second connector 81 with the proper alignment.When the corresponding second connector 110 is in proper alignment withthe second connector 81, the delivery device 90 is manipulated to insertthe corresponding second connector 110 at least partially in the secondconnector 81. Once the corresponding second connector 110 is inserted inthe second connector 81, the corresponding second connector 110 isbrought into locked engagement with the second connector 81 by rotatingthe corresponding second connector 110 within and relative to the secondconnector 82, for example by approximately 90 degrees.

Although the corresponding second connector 110 can take many suitableforms, in the example embodiments where the second or inner connector 81of the inner part 14 of the facet joint implant 10 comprises a secondbayonet connector 82, the corresponding second connector 110 of thedelivery device 90 comprises a second bayonet 111. The second bayonet111 is adapted and configured to be brought into engagement with and tobe inserted in the second bayonet connector 82. The second bayonet 111is inserted into the second bayonet connector 82 by inserting thebayonet into the open interior space 84 in the body 83 of the secondbayonet connector 82 through the open face 85 of the second bayonetconnector 82. The second bayonet 111 is adapted and configured to bebrought into locked engagement with the second bayonet connector 82 byrotating the second bayonet 111 relative to the second bayonet connector82, for example by approximately 90 degrees.

In the example embodiments, the corresponding second connector 110 ofthe delivery device 90 comprises a second key 113. The second key 113 isconfigured and operable to allow the corresponding second connector 110to be inserted in and withdrawn from the second connector 81 only whenthe corresponding second connector 110 and the second connector 81 arein a particular alignment, and not otherwise. In the example embodimentswhere the corresponding second connector 110 comprises the secondbayonet 111, the second bayonet comprises a t-shaped pin 112 as thesecond key 113. The t-shaped pin 112 is configured to correspond to theshape of the open face 85 of the second bayonet connector 82 of thesecond or inner connector 81 of the facet joint implant 10. That shapecan be, for example, a vertical slot shape. Accordingly, the t-shapedpin 112 allows the second bayonet 111 to be inserted into and withdrawnfrom the open interior space 84 in the body 83 of the second bayonetconnector 82 only when the t-shaped pin 112 is aligned in a particularorientation relative to the shape of the open face 85, e.g., thevertical slot, and otherwise blocks the second bayonet 111 from beinginserted or withdrawn. Accordingly, once the t-shaped pin 112 of thesecond bayonet 111 is inserted into the second bayonet connector 82 androtated to bring the corresponding second connector 110 into lockedengagement with the second connector 81, the t-shaped pin 112 preventsthe corresponding second connector 110 from inadvertently beingwithdrawn from the second connector 81.

It will be appreciated that while in the example embodiments, the secondkey 113 comprises a t-shaped pin 112 of a second bayonet 111, the secondkey may take many other forms consistent suitable to achieve theobjective described. It will also be appreciated that the t-shaped pin112 and the corresponding shape of the open face 85 of the secondbayonet connector 82 may have many variations suitable to achieve theobjective described. For example, other letter shapes, e.g. “H,” andother geometric shapes, e.g., a star shape, may be used.

To facilitate the proper alignment of the corresponding second connector110 of the delivery device 90 and the second connector 81 of the innerpart 14 of the facet joint implant 10, and as mentioned previously, theinner tube 105 of the delivery device 90 has an opening comprising awindow 104. The window 104 is located at the distal end portion 92 ofthe delivery device 90 and is spaced just proximally from thecorresponding first connector 100 of the delivery device 90. With thecorresponding first connector 100 of the delivery device 90 inengagement with and inserted in the first connector 51 of the outer part12 of the facet joint implant 10, the corresponding second connector 110of the delivery device 90 and the second connector 81 of the inner part14 of the facet joint implant 10 are at least partially visible throughthe window 104 as the corresponding second connector 110 is brought intoengagement with and inserted into the second connector 81. The window104 thus provides for the orientation of the corresponding secondconnector 110 relative to the second connector 81 to be checked visuallyand, if necessary, to be adjusted so that the corresponding secondconnector 110 can be brought into engagement with, inserted into, andbrought into locked engagement with the second connector 81 as describedabove.

When the corresponding second connector 110 of the delivery device 90 isin engagement with and inserted in the second connector 81 of the innerpart 14 of the facet joint implant 10, the delivery device 90 can bemanipulated as further described below to selectively impart motion tothe inner part 14 of the facet joint implant 10, including the wedge 61,to move distally relative to the outer part 12 of the facet jointimplant 10, including the first facet plate 20 and the second facetplate 30. Thus, the delivery device 90 can be manipulated to selectivelycause the facet joint implant 10 to distally expand from its closedstate to its open state in the manner described herein. It will beappreciated that because the wedge 61 is pushed in a distal direction,rather than pulled in a proximal direction, to cause the facet jointimplant 10 to distally expand to the open state, it is only necessaryfor the corresponding second connector 110 to be in engagement with andinserted in the second connector 81 of the facet joint implant 10 toachieve this effect. It is not necessary that the corresponding secondconnector 110 be in locked engagement with the second connector 81.Nevertheless, it is preferred for the corresponding second connector 110and the second connector 81 to be in locked engagement to avoidpotential inadvertent disengagement during a procedure. In addition, ifit is desired to pull the wedge 61 in the proximal direction to causethe facet joint implant 10 to distally retract to the closed state, forexample for removal or repositioning, the corresponding second connector110 and the second connector 81 must be in locked engagement.

When it is desired to unlock and disengage the delivery device 90 fromthe inner part 14 of the facet joint implant 10, the process describedabove is simply reversed. The corresponding second connector 110 of thedelivery device 90, and more specifically the second bayonet 111, isrotated in the opposite direction and then withdrawn from the secondconnector 81 of the facet joint implant 10, and more specifically thesecond bayonet connector 82.

As mentioned previously, the corresponding second connector 110 isfixedly connected or attached to the distal end of the inner shaft 115,which extends within the hollow outer tube 91, and more specificallywithin the hollow inner tube 105 within the hollow outer tube 91, fromthe corresponding second connector 110 at the distal end portion 92 ofthe delivery device 90 to the proximal end portion 93 of the deliverydevice 90. Preferably but not necessarily, the inner tube 105 and theinner shaft 115 are arranged to be substantially concentric.

The inner shaft 115 is selectively moveable within and relative to thehollow outer tube 91. More specifically, the inner shaft 115 isselectively movable at least in the direction of the distal end portion92 and the proximal end portion 93 of the delivery device 90 androtationally within and relative to the hollow outer tube 91. Still morespecifically, the inner shaft 115 is selectively moveable within andrelative to the hollow inner tube 105 within the hollow outer tube 91.Still more specifically the inner shaft 115 is selectively movable atleast in the direction of the distal end portion 92 and the proximal endportion 93 of the delivery device 90 and rotationally within andrelative to the hollow inner tube 105 within the hollow outer tube 91.

At the proximal end portion 93 of the delivery device 90, the innershaft 115 is movably connected or attached to the inner shaft controlknob 121 and to a lock switch 124 and a lock 162. The inner shaft 115and the corresponding second connector 110 are configured and adapted tobe controlled by the inner shaft control knob 121 and the lock switch124. More specifically, the movement of the inner shaft 115 and thecorresponding second connector 110 are controllable via manipulation ofthe inner shaft control knob 121 and the lock switch 124. Still morespecifically, the movement of the inner shaft 115 and the correspondingsecond connector 110 in the directions of the distal end portion 92 andthe proximal end portion 93 of the delivery device 90 and relative tothe outer tube 91, inner tube 105, and corresponding first connector 100are controllable via manipulation of the inner shaft control knob 121.The movement of the inner shaft 115 and the corresponding secondconnector 110 rotationally within and relative to the hollow outer tube91, the hollow inner tube 105, and the corresponding first connector 100is controllable via manipulation of the lock switch 124. The inner shaftcontrol knob 121 and the lock switch 124 are described further below.

It is preferred that the corresponding second connector 110 and theinner shaft 115 comprise a single monolithic structure. However, theinner shaft 115 can comprise a separate structure from the correspondingsecond connector 110. In that case, the corresponding second connector110 is preferably fixedly connected or attached to the inner shaft 115at the distal end of the delivery device 90 so that the inner shaft 115and the corresponding second connector 110 move together, e.g., when theinner shaft 115 is rotated within and relative to the hollow inner tube105 within the hollow outer tube 91, the corresponding second connector110 rotates the same, and when the inner shaft 115 is moved within andrelative to the hollow inner tube 105 within the hollow outer tube 91toward the distal end portion 92 or the proximal end portion 93 of thedelivery device 90, the corresponding second connector 110 moves thesame.

3. Outer Tube Control Knob.

The outer tube control knob 116 is located at the proximal end portion93 of the delivery device 90. The outer tube control knob 116 is fixedlycoupled with the hollow outer tube 91 via a fixed coupling 117. Theouter tube control knob 116 has a passageway 118 through which the innertube 105 extends. The outer tube control knob 116 is movably coupled tothe inner tube 105 via a threaded coupling 119 within the passageway118.

The outer tube control knob 116 is configured and is selectivelyoperable to control the outer tube 91 and to cause it to move toward thedistal end portion 92 and the proximal end portion 93 of the deliverydevice 90 relative to the inner tube 105 and the first correspondingconnector 100. Accordingly, the outer tube control knob 116 isconfigured and is selectively operable to cause the holding arms 95,including the flat portions 96 and support surfaces 97, to move towardthe distal end portion 92 and the proximal end portion 93 of thedelivery device 90.

The outer tube control knob 116 is configured and is selectivelyoperable to cause the outer tube 91 and the holding arms 95, includingthe flat portions 96, and the support surfaces 97, to move toward thedistal end portion 92 of the delivery device 90 by rotating the outertube control knob 116 in a first direction. This causes the outer tubecontrol knob 116 to translate on the threaded coupling 119 with theinner tube 105 in the direction of the distal end portion 92 and thuscauses the outer tube 91 and the holding arms 95 to move in thedirection of the distal end portion 92 relative to the inner tube 105and the first corresponding connector 100 of the delivery device 90.

Similarly, the outer tube control knob 116 is configured and isselectively operable to cause the outer tube 91 and the holding arms 95,including the flat portions 96 and the support surfaces 97, to movetoward the proximal end portion 93 of the delivery device 90 by rotatingthe outer tube control knob 116 in a second direction opposite to thefirst direction. This causes the outer tube control knob 116 totranslate on the threaded coupling 119 with the inner tube 105 in thedirection of the proximal end portion 93 and thus causes the outer tube91 and the holding arms 95 to move in the direction of the proximal endportion 92 relative to the inner tube 105 and the first correspondingconnector 100 of the delivery device 90.

When the first corresponding connector 100 is in engagement with andinserted in the first connector 51 of the facet joint implant 10, theouter tube control knob 116 is configured and is selectively operable tobe rotated in the first direction to cause the outer tube 91 to movetoward the distal end portion 92 of the delivery device 90, the flatportions 96 of the holding arms 95 to advance over the flats 57 on thebody 53 of the first connector 51 of the facet joint implant 10, and thesupport surfaces 97 of the holding arms 95 to advance toward thesurfaces surrounding the open face 55 of the body 53 of the firstconnector 51. When the corresponding first connector 100 is brought intolocked engagement with the first connector 51, the body 53 of the firstconnector 51 is urged into engagement with the support surfaces 97.Similarly, the outer tube control knob 116 is configured and isselectively operable to be rotated in the second direction opposite tothe first direction to cause the outer tube 91 to move toward theproximal end portion 93 of the delivery device 90, the flat portions 96of the holding arms 95 to withdraw with respect to the flats 57 on thebody 53 of the first connector 51, and the support surfaces 97 of theholding arms 95 to withdraw from the body 53 of the first connector 51.

4. Control Handle.

The control handle 120 is located at the proximal end portion 93 of thedelivery device 90. The control handle 120 is fixedly coupled with thehollow inner tube 105 and hence with the corresponding first or outerconnector 100 of the delivery device 90. The control handle 120 isconfigured and selectively operable to bring the corresponding firstconnector 100 of the delivery device 90 into locked engagement with thefirst connector 51 of the first delivery device interface 50 of theouter part 12 of facet joint implant 10 in the manner described above.

The control handle 120 is fixedly connected to the inner tube 105 at theproximal end portion 93 of delivery device 90 and is configured andselectively operable to control the inner tube 105 and the correspondingfirst connector 100. More specifically, by manipulating the controlhandle 120, the movement of the inner tube 105 and the correspondingfirst connector 100 are controllable at least to an extent. Still morespecifically, at least when the corresponding second or inner connector110 of the delivery device 90 is not in locked engagement with thesecond or inner connector 81 of the facet joint implant 10, the controlhandle 120 can be rotated to cause the corresponding first connector 100to rotate relative to the hollow outer tube 91 of the delivery device90.

The delivery device 90 and control handle 120 can be manipulated tobring the corresponding first connector 100 of the delivery device 90into engagement and into locked engagement with the first connector 51of the first delivery device interface 50 of the facet joint implant 10in the following manner. The delivery device 90 is moved distallyrelative to the facet joint implant 10, or vice versa, to cause thecorresponding first connector 100 of the delivery device to be broughtinto engagement with and inserted in the first connector 51 of the facetjoint implant 10 in the manner described herein. The control handle 120is then rotated, for example by about 90 degrees to cause thecorresponding first connector 100 to rotate in and relative to the firstconnector 51 and bring the corresponding first connector 100 into lockedengagement with the first connector 51. The outer tube 91 of thedelivery device 90 is manipulated to align the flat portions 96 on theholding arms 95 at the distal end portion 92 of the delivery device 90with the flats 57 on the exterior surface 56 of the first connector 51of the facet joint implant 10. The outer tube control knob 116 isrotated to advance the holding arms 95 over the flats 57. To unlock anddisengage the corresponding first connector 100 from the first connector51, the delivery device 90 and control handle 120 are manipulated tosimply reverse the process described.

5. Inner Shaft Control Knob.

The inner shaft control knob 121 is located at the proximal end portion93 of the delivery device 90 and is movably coupled with the controlhandle 120, with the inner shaft 115, and via the inner shaft 115 withthe corresponding second or inner connector 110 of the delivery device90.

More specifically, the inner shaft control knob 121 is rotatablyconnected to the control handle 120 at the proximal end portion 93 ofthe delivery device 100 and is free to rotate relative to the controlhandle 120 but is not free to move toward the distal end portion 92 orthe proximal end portion 93 of the delivery device 90. The inner shaftcontrol knob 121 is also movably connected to the inner shaft 115 andvia the inner shaft 115 to the corresponding second connector 110 at theproximal end portion 93 of the delivery device 90. Still morespecifically, in the example embodiments the inner shaft has a threadedproximal end portion 114 and the inner shaft control knob 121 has athreaded passageway 122. The threaded proximal end portion 114 of theinner shaft 115 extends through the control handle 120 and into thethreaded passageway 122, which comprises a threaded coupling 122 to theinner shaft 115. The inner shaft control knob 121 is free to rotate onthe inner shaft 115 via the threaded coupling.

The inner shaft control knob 121 is configured and is selectivelyoperable to control the inner shaft 115 and the corresponding secondconnector 110. More specifically, the inner shaft control knob 121 isconfigured and is selectively operable to control the movement of theinner shaft 115 and the corresponding second connector 110 in thedirections of the distal end portion 92 and the proximal end portion 93of the delivery device 90. Even more specifically, the inner shaftcontrol knob 121 is selectively rotatable relative to the inner shaft115 and is selectively operable by being rotated to cause the innershaft 115 and the corresponding second connector 110 to move toward thedistal end portion 92 and the proximal end portion 93 of the deliverydevice 90 relative to the control handle 120, the hollow outer tube 91,and the inner tube 105 and the corresponding first connector 100 of thedelivery device 90. Rotation of the inner shaft control knob 121 on theinner shaft 115 via the threaded coupling causes the inner shaft 115 andthe corresponding second or inner connector 110 of the delivery device90 to translate in the direction of the distal end portion 92 and theproximal end portion 93 depending on the direction the inner shaftcontrol knob 121 is rotated.

The inner shaft control knob 121 is thus configured and operable whenrotated in a first direction to selectively cause the correspondingsecond connector 110 to move toward the distal end portion 92 of thedelivery device 90 and to be brought into engagement with and insertedin the corresponding second connector 110 in the second connector 81 ofthe facet joint implant 10 in the manner described herein. The innershaft control knob 121 also is configured and operable when rotated in asecond direction opposite to the first direction to selectively causethe corresponding second connector 110 to move toward the proximal endportion 93 of the delivery device 90 and to be brought out of engagementwith and withdraw from the second connector 81 of the facet jointimplant 10 in the manner described herein.

The inner shaft control knob 121 is also configured and operable whenrotated in a first direction to selectively cause the facet jointimplant 10 to distally expand into its open position. Thus, the innershaft control knob 121 is configured and operable when rotated in thefirst direction to selectively cause the corresponding second connector110 of the delivery device 90 to move toward the distal end portion 92of the delivery device 90, in turn causing the inner part 14 of thefacet joint implant 10, and more specifically the wedge 61, to movedistally relative to the outer part 12 of the facet joint implant 10,and more specifically the first facet plate 20 and the second facetplate 30, and the facet joint implant 10 to distally expand to its openstate in the manner described previously.

Similarly, the inner shaft control knob 121 is configured and operablewhen rotated in a second direction opposite to the first direction toselectively cause the corresponding second connector 110 of the deliverydevice 90 to move toward the proximal end portion 93 of the deliverydevice 90, in turn causing the inner part 14 of the facet joint implant10, and more specifically the wedge 61, to move proximally relative tothe outer part 12 of the facet joint implant 10, and more specificallythe first facet plate 20 and the second facet plate 30, and the facetjoint implant 10 to distally contract to its closed state in the mannerdescribed previously.

As mentioned previously, because rotating the inner shaft control knob121 in the first direction effectively pushes the corresponding secondconnector 110 of the delivery device 90 in the distal direction, thecorresponding second connector 110 need only be in engagement with andinserted in the second connector 81 of the facet joint implant 10 whilethe inner shaft control knob 121 is rotated in the first direction tocause the facet joint implant 10 to distally expand to the openposition. The corresponding second connector 110 need not be in lockedengagement with the second connector 81. However, the correspondingsecond connector 110 must be in locked engagement with the secondconnector 81 when the inner shaft control knob 121 is rotated in thesecond direction in order to cause the facet joint implant 10 todistally contract to the closed position. If the corresponding secondconnector 110 is not in locked engagement with the second connector 81,rotation of the inner shaft control knob 121 in the second directionsimply moves the corresponding second connector 110 toward the proximalend portion 93 of the delivery device 90 and brings the correspondingsecond connector 110 out of engagement with the second connector 81.

6. Lock Switch and Lock.

The lock switch 124 and lock 126 of the delivery device 90 are locatedat the proximal end portion 93 of the delivery device 90. The lockswitch 124 and lock 126 are coupled with the inner shaft 115 and via theinner shaft 115 with the corresponding second connector 110 of thedelivery device 90.

The lock switch 124 is configured and operable to selectively rotate thecorresponding second connector 110 of the delivery device 90 relative tothe second connector 81 of the facet joint implant 10 in order to bringthe corresponding second connector 110 into and out of locked engagementwith the second connector 81, depending on the direction the lock switch124 is rotated. The lock 126 is responsive to the operation of the lockswitch 124 and is configured and operable to hold or lock thecorresponding second connector 110 in the locked engagement position toprevent the inadvertent rotation of the corresponding second connector110 from the locked engagement position and potential unlocking anddisengagement from the second connector 81.

More specifically, the lock switch 124 is configured and operable to bemanipulated to rotate approximately 90 degrees between a first positionand a second position relative to the control handle 120, the hollowouter tube 91, and the inner tube 105 and corresponding first connector100 of the delivery device 90. Rotation of the lock switch 124approximately 90 degrees between the first position and the secondposition also rotates the inner shaft 115 and the corresponding secondconnector 110 by approximately 90 degrees relative to the control handle120, the hollow outer tube 91, and the inner tube 105 and correspondingfirst connector 100.

Most importantly, however, when the corresponding second connector 110of the delivery device 90 is in engagement with and inserted in thesecond connector 81 of the facet joint implant 10 in the mannerdescribed above, rotation of the lock switch 124 approximately 90degrees from the first position to the second position rotates thecorresponding second connector 110 approximately 90 degrees relative toand within the second connector 81 and brings the corresponding secondconnector 110 into locked engagement with the second connector 81.Similarly, when the lock switch 124 is rotated from the second positionto the first position, the corresponding second connector 110 rotatesapproximately 90 degrees relative to and within the second connector 81and brings the corresponding second connector 110 and second connector81 out of locked engagement. Thus, when the corresponding secondconnector 110 is in engagement with and inserted in the second connector81, the first position of the lock switch 124 corresponds to an unlockedengagement position, and the second position corresponds to a lockedengagement position.

In response to the lock switch 124 being rotated approximately 90degrees from the first position (unlocked) to the second position(locked), the lock 126 is configured and operable to temporarily hold orlock the corresponding second connector 110 in the approximately 90degree rotated second position relative to the control handle 120, thehollow outer tube 91, and the inner tube 105 and corresponding firstconnector 100. More importantly, when the corresponding second connector110 of the delivery device 90 is in engagement with and inserted in thesecond connector 81 of the facet joint implant 10 in the mannerdescribed above, the lock 126 is configured and operable to temporarilyhold or lock the corresponding second connector 110 in the approximately90 degree rotated second (locked) position relative to the secondconnector 81, i.e., in the locked engagement position.

Still more specifically, in the example embodiments the lock switch 124comprises a rotatable lever 125 that is seated and is rotatable in aslot 123 of the control handle 120. Also, as best seen in FIG. 17, andas also seen at least partially in FIGS. 22A, 23D, and 24B, the lock 126comprises a detent mechanism 127 that is coupled to the lock switch 124,and that more specifically is coupled to the rotatable lever 125 and tothe control handle 120. Even more specifically, the detent mechanism 127comprises a spring-loaded ball plunger 128 that is connected or attachedto the lock switch 124, and more specifically to the rotatable lever125, and a ball detent 129 that is located on the control handle 120 andmore specifically in the slot 123 of the control handle 120.

The slot 123 extends approximately 90 degrees around the control handle120 with one end of the slot 123 corresponding to the first (unlocked)position of the lock switch 124 and the other end corresponding to thesecond (locked) position of the lock switch 124. The lock switch 124,and more specifically the rotatable lever 125, is configured andoperable to be rotated approximately 90 degrees in the slot 123 betweenthe first (unlocked) and second (locked) positions.

The inner shaft 115 passes through and is engaged by the lock switch124, and more specifically the lever 125. The inner shaft 115 is engagedby the lock switch 124, and more specifically the lever 125, in such away that it is free to move toward the distal end portion 92 and theproximal end portion 93 of the delivery device 90 relative to the lockswitch 124, and more specifically the lever 125, but rotates with thelock switch 124, and more specifically the lever 125.

Thus, when the lock switch 124, and more specifically the lever 125, isrotated approximately 90 degrees in the slot 123 from the first(unlocked) to the second (locked position), the inner shaft 115 and thecorresponding second connector 110 are rotated approximately 90 degreesas described above. More importantly, when the corresponding secondconnector 110 of the delivery device 90 is in engagement with andinserted in the second connector 81 of the facet joint implant 10,rotation of the lock switch 124, and more specifically the lever 125,approximately 90 degrees in the slot 123 from the first (unlocked) tothe second (locked) position rotates the corresponding second connector110 within and relative to the second connector 81 and bringscorresponding second connector 110 into locked engagement with thesecond connector 51.

The lock 126, and more specifically the ball plunger 128 of the detentmechanism 127, rotates with the lock switch 124, and more specificallythe rotatable lever 125. When the lock switch 124, and more specificallythe lever 125, is rotated approximately 90 degrees in the slot 123 fromthe first (unlocked) to the second (locked) position, the ball of theball plunger 128 is pushed into engagement with the ball detent 129 inthe slot 123 under the pressure of the spring of the ball plunger 128.This holds or locks the lock switch 124 in the approximately 90 degreerotated second position, which holds or locks the inner shaft 115 andcorresponding second connector 110 in the approximately 90 degreerotated second (locked) position relative to the control handle 120, thehollow outer tube 91, and the inner tube 105 and corresponding firstconnector 100 of the delivery device 90. Most importantly however, whenthe corresponding second connector 110 of the delivery device 90 is inengagement with and inserted in the second connector 81 of the facetjoint implant 10 in the manner described above, it holds or locks thecorresponding second connector 110 in the approximately 90 degreerotated second (locked) position relative to and within the secondconnector 81, i.e., in the locked engagement position.

In order to bring the corresponding second connector 110 out of lockedengagement with the second connector 81, the process described above issimply reversed. That is, sufficient force is applied to the lever 125of the lock switch 124 to overcome the force of the ball detent 129mechanism and rotate the lock switch 124 in the opposite direction inthe slot 123 approximately 90 degrees from the second (locked) to thefirst (unlocked) position. This rotates the corresponding secondconnector 110 approximately 90 degrees in the opposite direction andbrings it out of locked engagement with the second connector 81 of thefacet joint implant 10. The inner shaft control knob 121 can then bemanipulated as described above to withdraw the corresponding secondconnector 110 from engagement with the second connector 81.

E. Operation of Preferred Embodiment.

In use of the distally expanding facet joint implant 10 and deliverydevice 90, a facet joint 140 in which the facet joint implant 10 is tobe implanted is first prepared to receive the facet joint implant 10. Itis noted that while facet joint 140 and facet joint implant 10 arereferred to here in the singular, such reference is for ease ofdiscussion only and is not meant to be limiting. Persons skilled in theart will realize that each cervical vertebra includes a pair oflaterally spaced facet joints. Accordingly, it is likely, although notnecessarily always the case, that multiple facet joints must be preparedand multiple facet joint implants implanted in a given procedure. Thus,reference to facet joint and facet joint implant in the singular is notmeant to exclude, but rather to encompass multiple facet joints, facetjoint implants, and the procedures used to prepare multiple facet jointsand implant multiple facet joint implants.

The manner and tools for preparing an intervertebral joint to receive animplant are well known to those skilled in the art and need not bedescribed in detail. Briefly, various known joint preparation tools maybe used to prepare an affected facet joint and these may be delivered tothe joint posteriorly through a small incision using a suitable guidewire or pin. The tools may be delivered percutaneously under X-rayguidance, under direct vision, under endoscopic guidance, or through apreviously inserted hollow needle, for example.

Commonly employed tools include one or more chisels for cutting thejoint capsule and other tissues as necessary or desired to facilitatesubsequent insertion of the facet implant in the joint. A rasp may beused to roughen the external boney surfaces of the facets facing thefacet joint 140 as necessary or desired to facilitate the implantadhering to the bony surfaces. One or more dilators may be used todilate the facet joint 140 to facilitate delivery of the facet jointimplant 10 to the affected facet joint 140. Dilators of successivelylarger sizes in all three dimensions can be used sequentially until thenecessary or desired dilation is achieved.

In preparation for implanting the facet joint implant 10, the facetjoint implant 10 is connected to the distal end portion 92 of thedelivery device 90 with the facet joint implant 10 in its closed state.With reference to FIGS. 21 through 22B among others, the delivery device90 is manipulated to bring the corresponding first connector 100 of thedelivery device 90 into engagement with the first connector 51 of thefacet joint implant 10 and insert the corresponding first connector 100into the first connector 51 of the facet joint implant 10. The controlhandle 120 of the delivery device 90 is rotated by approximately 90degrees to bring the corresponding first connector 100 into lockedengagement with the first connector 51. The outer tube 91 of thedelivery device 90 is then manipulated to align the flat portions 96 ofthe holding arms 95 of the delivery device 90 with the flats 57 on thebody 53 of the first connector 51 and the outer tube control knob 116 isrotated to advance the holding arms 95 toward the distal end portion 92of the delivery device 90 and push the support surfaces 97 of theholding arms 95 into secure engagement with the first connector 51.

Next, with reference to FIGS. 23A through 23E among others, thecorresponding second or inner connector 110 of the delivery device 90 isbrought into locked engagement with the second or inner connector 81 ofthe facet joint implant 10. With the lock switch 124 of the deliverydevice 90 in the first (unlocked) position, the inner shaft control knob121 of the delivery device 90 is rotated as to advance the correspondingsecond or inner connector 110 of the delivery device 90 distally intoengagement with the second connector 81 of the facet joint implant 10and to insert the t-shaped pin 112 of the second bayonet 111 into theopen interior space 84 in the body 83 of the second bayonet connector 82of the second or inner connector 81 of the facet joint implant 10.Proper alignment of the corresponding second or inner connector 110 andthe second or inner connector 81 can be visually confirmed in the window104 of the inner tube 105 of the delivery device 90.

With the corresponding second connector 110 in engagement with andinserted in the second connector 81, the lock switch 124 on the deliverydevice 90 is rotated approximately 90 degrees from the first (unlocked)position to the second (locked) position. This brings the correspondingsecond connector 110 into locked engagement with the second connector81. The inner shaft control knob 121 can then be rotated in a firstdirection to cause the corresponding second connector 110 and the secondconnector 81 to advance distally, push the wedge 61 of the inner part 14of the facet joint implant 10 forward distally relative to the firstfacet plate 20 and the second facet plate 30 of the outer part 12 of thefacet joint implant 10, and thus cause the facet joint implant 10 todistally expand to its open position.

Optionally, an inter-facet connection plate 130 can be used with thefacet joint implant 10 if desired. As illustrated in FIGS. 27A through29E, a suitable inter-facet connection plate 130 may comprise a thinelongated plate 131 with a first opening 132, one or more secondopenings 133, and one or more third openings 134.

The first opening 132 is preferably located approximately centrally onthe plate 131, but may be offset from a central location as desired. Thefirst opening 132 is dimensioned and configured to permit at least theouter part 12 and the inner part 14 of the facet joint implant 10 topass through the first opening 132 and into an adjacent facet joint 140when the first opening 132 is aligned with a posterior opening 141 ofthe facet joint 140. The first opening 132 is also dimensioned andconfigured to block at least the first or outer connector 51 of thefacet joint implant 10 from passing through the first opening 132 andentering the facet joint 140. This helps provide suitable positioning ofthe facet joint implant 10 in the facet joint 140 by helping to preventthe facet joint implant 10 from being over-inserted into the facet joint140.

The one or more second openings 133 are located on the plate 131relative to the first opening 132 so that when the first opening 132 isaligned with the posterior opening 141 of the facet joint 140, the oneor more second openings 133 are positioned adjacent to the bony externalsurface 142 of the facet 143 superior to the facet joint 140. Similarly,the one or more third openings 134 are located on the plate 131 relativeto the first opening 132 so that when the first opening 132 is alignedwith the posterior opening 141 of the facet joint 140, the one or morethird openings 134 are positioned adjacent the bony external surface 144of the facet 145 inferior to the facet joint 140. Accordingly, thelengthwise dimension of the inter-facet connection plate 130 ispreferably selected to be sufficient to span the posterior opening 141of the facet joint 140 with the second and third openings 133, 134located adjacent to the bony external surfaces 142, 144 of the superiorand inferior facets 143, 145 when the first opening 132 is aligned withthe posterior opening 141 of the facet joint 140.

The one or more second openings 133 and the one or more third openings134 are dimensioned and configured to accept suitable screws 146 orother suitable fasteners so that the inter-facet connection plate 130can be fixedly attached to and between the superior and inferior facets143, 145 above and below the facet joint 140 with the facet jointimplant 10 positioned in the facet joint 140 as illustrated in FIGS. 28Athrough 29E for example. To accommodate different vertebralphysiologies, and for ease of adjustability during an implant procedure,the second and third openings 133, 134 can comprise a plurality ofslightly overlapping openings. This permits the inter-facet connectionplate 130 to be attached to the adjacent upper and lower facets 143, 145at slightly different locations, and also provides a degree ofadjustability to the entry angle and position of the facet joint implant10 relative to the posterior opening 141 of the facet joint 140.

The inter-facet connection plate 130, if used, functions together withthe distal expansion of the facet joint implant 10 to help stabilize thefacet joint 140, help return or maintain the cervical spine in thelocality of the facet joint 140 to proper alignment, and help inenhancing facet fusion by fixing the adjacent facets together. Theinter-facet connection plate 130 may be constructed of any material thatis suitable for long-term implantation in the body of a patient, andthat is relatively strong and rigid, but also malleable enough to beshaped as necessary or desired to achieve the objectives noted above.One example of an inter-facet connection plate 130 shaped for use inconnection with implantation of a facet joint implant in the facet jointbetween cervical vertebrae C4-C5 is illustrated in FIG. 28B. Anotherexample is shown in FIGS. 29C-29D.

Once the facet joint implant 10 is connected at the distal end portion92 of the delivery device 90 as described above, the delivery device ismanipulated to introduce the facet joint implant 10 through the incisionand to direct it through the dilated passage to the facet joint 140 inwhich it is to be implanted. As is known to persons skilled in the art,various means are available for visually or otherwise tracking the facetjoint implant 10 as it is directed to the facet joint 140, includingvarious means identified above.

If an inter-facet connection plate 130 is used, the outer part 12 of thefacet joint implant 10 is passed through the first opening 132 in theinter-facet connection plate 130 before being introduced through theincision. In that case, the delivery device 90 is manipulated tointroduce the facet joint implant 10 and the inter-facet connectionplate 130 together through the incision and the dilated passage to thefacet joint 140.

At the facet joint 140, the delivery device 90 is manipulated toposition and orient the facet joint implant 10 relative to the posterioropening 141 of the facet joint 140 as desired, and then to insert thefacet joint implant 10 into the facet joint 140 as illustrated in FIGS.28A and 29A. As described herein, preferably the first or outer firstconnector 51 of the facet joint implant 10 is dimensioned to be largerthan the intended posterior spacing between the superior and inferiorfacets 143, 145, in other words larger than the intended posterioropening 141 of the facet joint 140. This feature helps provide suitablepositioning of the facet joint implant 10 in the facet joint 140 byallowing the outer part 12 and the inner part 14 of the facet jointimplant 10 to be positioned in the facet joint 140, but helps preventthe facet joint implant 10 from being over-inserted into the facet joint140.

If an inter-facet connection plate 130 is used, the delivery device 90can be manipulated to hold the facet joint implant 10 in the desiredposition while a hole 147 is drilled in the external surface 142 of thefacet 143 superior to the facet joint 140 and a screw 146 is inserted toattach the inter-facet connection plate 130 to the superior facet 143 asshown in FIGS. 29A-29D. Similarly, a hole 148 is drilled in the facet145 inferior to the facet joint 140 and a screw 146 is inserted toattach the inter-facet connection plate 130 to the inferior facet 145 asshown in FIGS. 29A-29D. As also shown in FIGS. 29C-29E, the inter-facetconnection plate 130 can be shaped as necessary to help achieve thedesired stabilization and alignment of the facet joint 140 and theadjacent vertebrae.

Methods for drilling holes and securing screws or other suitablefasteners in in bone, such as vertebrae, are well known to personsskilled in the art and need not be described here. Similarly, variousdrills, drill guides, etc. are well known for this purpose and need notbe described here.

Once the facet joint implant 10 is properly positioned in the facetjoint 140 and the inter-facet connection plate 130 is secured and shaped(if one was used), the delivery device 90 is manipulated in the mannerdescribed above and as illustrated in FIGS. 25A, 25B, and others todistally expand the facet joint implant 10 and distally distract thefacet joint 140 as illustrated in FIGS. 28B and 29E. With the lockswitch 124 of the delivery device 90 in the second (locked) position,the inner shaft control knob 121 of the delivery device 90 is rotated inthe first direction to cause the facet joint implant 10 to distallyexpand from the closed state to the open state in the manner previouslydescribed herein. Preferably, the inner shaft control knob 121 isrotated until the facet joint implant 10 reaches its fully distallyexpanded open state as illustrated in FIGS. 28B and 29E, the first setof teeth 40 on the outer part 12 of the facet joint implant 10 engagethe second set of indents 74 on the inner part 14 of the facet jointimplant 10, and a physical feedback, for example a click, is sensed.

With the facet joint implant 10 properly positioned in the facet joint140 in the fully distally expanded open state, the first exteriorsurface 24 of the first facet plate 20 will preferably be in substantialphysical contact with an anterior portion 149 of the interior surface150 of the superior facet 143 facing the facet joint 140, and the secondexterior surface 34 of the second facet plate 30 will preferably be insubstantial physical contact with an anterior portion 151 of theinterior surface 152 of the inferior facet 145 facing the facet joint140 as seen in FIGS. 28B and 29E. In this position, the first pluralityof serrations 25 on the first exterior surface 24 of the first facetplate 20 and the second plurality of serrations 35 on the secondexterior surface 34 of the second facet plate 30 help adhere the facetjoint implant 10 to the bony surfaces of the superior and inferiorfacets 143, 145 facing the facet joint 140.

If the position of the facet joint implant 10 in the facet joint 10 isnot as desired, however, the delivery device 90 may be manipulated todistally contract the facet joint implant 10 and to reposition the facetjoint implant 10 in the facet joint 140. With the lock switch 124 on thedelivery device 90 in the second (locked) position, the inner shaftcontrol knob 121 on the delivery device is rotated in the directionopposite to the direction it was rotated to expand the facet jointimplant 10. Preferably, the inner shaft control knob 121 is rotated inthe opposite direction until the facet joint implant 10 has distallycontracted sufficiently to be repositionable within the facet joint 140or removed from the facet joint 140 if desired. The delivery device 90can then be manipulated to reposition the facet joint implant 10 in thefacet joint 140 as desired. Once the facet joint implant 10 is in thedesired position, the delivery device can be manipulated to distallyre-expand the facet joint implant 10 in the manner previously described.

Once the facet joint implant 10 is properly positioned in the facetjoint 140 as desired and in its distally expanded open state, thedelivery device 90 may be disconnected from the facet joint implant 10,and may be withdrawn posteriorly from the body of the patient throughthe dilated passageway and posterior incision. The delivery device 90 isdisconnected from the facet joint implant 10 by simply reversing theorder of the steps described above to connect the delivery device 90 tothe facet joint implant 10.

If desired or necessary, additional steps can be performed beforecompleting the procedure and closing the posterior incision. Forexample, bone paste may have been introduced in the facet joint 140before the facet joint implant 10 was introduced to facilitate jointfusion in the future. The first opening 23 in the first facet plate 20and the second opening 33 in the second facet plate 30 facilitate thedispersion of the bone paste or other medicinal or therapeuticsubstances in the facet joint 140, and also facilitate the growth ofnatural bone in, around, and through the facet joint implant 10. This inturn helps fuse the facets 143, 145 of the vertebrae adjacent to thefacet joint 140 and further stabilize and strengthen the facet joint 140and adjacent vertebrae.

A particularly beneficial effect of the distal expansion of the facetjoint implant 10 as described is that the facet joint 140 is distracteddistally, which results in widening of both the intervertebral discspace and intervertebral foramina and provides relief from the symptomsof cervical radiculopathy. Another possibly beneficial effect is thatdistraction of the facet joint 140 distally may help maintain thenatural lordotic alignment of the cervical spine while avoiding thecondition of kyphosis. This effect may be further enhanced by the use ofinter-facet connection plate as described herein.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar to or equivalent to those described herein can be used in thepractice or testing of the distally expanding facet implant and deliverydevice, suitable methods and materials are described above. Allpublications, patent applications, patents, and other referencesmentioned herein are incorporated by reference in their entirety to theextent allowed by applicable law and regulations. The distally expandingfacet implant and delivery device may be embodied in other specificforms without departing from the spirit or essential attributes thereof,and it is therefore desired that the present embodiment be considered inall respects as illustrative and not restrictive. Any headings utilizedwithin the description are for convenience only and have no legal orlimiting effect.

What is claimed is:
 1. A facet joint implant, comprising: an outer part,wherein the outer part comprises a first facet plate, a second facetplate, and a hinge connecting the first facet plate and the second facetplate; wherein the first facet plate has a first distal end portion anda first proximal end portion; wherein the second facet plate has asecond distal end portion and a second proximal end portion; wherein thehinge is located between the first proximal end portion of the firstfacet plate and the second proximal end portion of the second facetplate; wherein the hinge has a first axis of rotation; wherein the hingeconnects the first proximal end portion of the first facet plate and thesecond proximal end portion of the second facet plate in close proximityto and for rotation about the first axis of rotation; wherein the hingeis configured to prevent the first proximal end portion of the firstfacet plate and the second proximal end portion of the second facetplate from moving out of the close proximity; and an inner part movablypositioned within the outer part in a linear path, wherein the innerpart comprises a wedge and an interface, wherein the wedge includes athird distal end portion and a third proximal end portion, and whereinthe interface is adapted to be selectively brought into lockedengagement with a delivery device; wherein when the inner part is inlocked engagement with the delivery device the inner part is adapted tobe movable toward the first distal end portion of the first facet plateand the second distal end portion of the second facet plate by pushingthe inner part with the delivery device in a linear motion along thelinear path and the third distal end portion of the wedge directlyengages the first facet plate and the second facet plate so that thefirst distal end portion of the first facet plate and the second distalend portion of the second facet plate move apart; wherein when the innerpart is in locked engagement with the delivery device the inner part isadapted to be movable toward the first proximal end portion of the firstfacet plate and the second proximal end portion of the second facetplate by pulling the inner part with the delivery device in a linearmotion along the linear path and the first distal end portion of thefirst facet plate and the second distal end portion of the second facetplate move toward each other.
 2. The facet joint implant of claim 1,wherein the hinge comprises a living hinge.
 3. The facet joint implantof claim 1, wherein the inner part further comprises an elongatedconnector that extends through an opening within the hinge, and whereinthe elongated connector extends between the interface and the wedge. 4.The facet joint implant of claim 3, wherein the elongated connector isconcentric with the wedge and the interface.
 5. The facet joint implantof claim 1, wherein the first facet plate, the second facet plate, andthe hinge comprise a monolithic structure.
 6. The facet joint implant ofclaim 1, wherein the first facet plate has a first exterior surface witha first plurality of serrations or a first plurality of protrusions, andwherein the second facet plate has a second exterior surface with asecond plurality of serrations or a second plurality of protrusions. 7.The facet joint implant of claim 1, wherein the first facet plate has afirst interior surface and the second facet plate has a second interiorsurface, wherein the wedge has a third exterior surface and a fourthexterior surface, and wherein when the inner part is moved toward thefirst distal end portion of the first facet plate and the second distalend portion of the second facet plate the third exterior surface of thewedge directly engages the first interior surface of the first facetplate, and the fourth exterior surface of the wedge directly engages thesecond interior surface of the second facet plate.
 8. The facet jointimplant of claim 1, wherein the first facet plate has a first interiorsurface having a first sloped portion, wherein the second facet platehas a second interior surface having a second sloped portion, whereinthe wedge has a third exterior surface having a third sloped portionadapted to directly engage and move relative to the first sloped portionof the first interior surface of the first facet plate, and wherein thewedge has a fourth exterior surface having a fourth sloped portionadapted to directly engage and move relative to the second slopedportion of the second interior surface of the second facet plate.
 9. Afacet joint implant, comprising: an outer part, wherein the outer partcomprises a first facet plate, a second facet plate, and a hingeconnecting the first facet plate and the second facet plate; wherein thefirst facet plate has a first distal end portion and a first proximalend portion; wherein the second facet plate has a second distal endportion and a second proximal end portion; wherein the hinge is locatedbetween the first proximal end portion of the first facet plate and thesecond proximal end portion of the second facet plate; wherein the hingehas a first axis of rotation; wherein the hinge connects the firstproximal end portion of the first facet plate and the second proximalend portion of the second facet plate in close proximity to and forrotation about the first axis of rotation; wherein the hinge isconfigured to prevent the first proximal end portion of the first facetplate and the second proximal end portion of the second facet plate frommoving out of the close proximity; and an inner part movably positionedwithin the outer part in a linear path, wherein the inner part comprisesa wedge and an interface, wherein the wedge includes a third distal endportion and a third proximal end portion; wherein when the inner part isin locked engagement with a delivery device the inner part is adapted tobe movable toward the first distal end portion of the first facet plateand the second distal end portion of the second facet plate by pushingthe inner part with the delivery device in a linear motion along thelinear path and the third distal end portion of the wedge directlyengages the first facet plate and the second facet plate so that thefirst distal end portion of the first facet plate and the second distalend portion of the second facet plate move apart.
 10. The facet jointimplant of claim 9, wherein the hinge comprises a living hinge.
 11. Thefacet joint implant of claim 9, wherein the inner part further comprisesan elongated connector that extends through an opening within the hinge,and wherein the elongated connector extends between the interface andthe wedge.
 12. The facet joint implant of claim 11, wherein theelongated connector is concentric with the wedge and the interface. 13.The facet joint implant of claim 9, wherein the first facet plate, thesecond facet plate, and the hinge comprise a monolithic structure. 14.The facet joint implant of claim 9, wherein the first facet plate has afirst exterior surface with a first plurality of serrations or a firstplurality of protrusions, and wherein the second facet plate has asecond exterior surface with a second plurality of serrations or asecond plurality of protrusions.
 15. The facet joint implant of claim 9,wherein the first facet plate has a first interior surface and thesecond facet plate has a second interior surface, wherein the wedge hasa third exterior surface and a fourth exterior surface, and wherein whenthe inner part is moved toward the first distal end portion of the firstfacet plate and the second distal end portion of the second facet platethe third exterior surface of the wedge directly engages the firstinterior surface of the first facet plate, and the fourth exteriorsurface of the wedge directly engages the second interior surface of thesecond facet plate.
 16. The facet joint implant of claim 9, wherein thefirst facet plate has a first interior surface having a first slopedportion, wherein the second facet plate has a second interior surfacehaving a second sloped portion, wherein the wedge has a third exteriorsurface having a third sloped portion adapted to directly engage andmove relative to the first sloped portion of the first interior surfaceof the first facet plate, and wherein the wedge has a fourth exteriorsurface having a fourth sloped portion adapted to directly engage andmove relative to the second sloped portion of the second interiorsurface of the second facet plate.
 17. A facet joint implant,comprising: a first facet plate having a first distal end portion and afirst proximal end portion; a second facet plate having a second distalend portion and a second proximal end portion; a hinge connecting thefirst proximal end portion of the first facet plate and the secondproximal end portion of the second facet plate for rotation about afirst axis of rotation; a wedge movably positioned in a linear pathbetween the first facet plate and the second facet plate, wherein thewedge engages the first facet plate and the second facet plate; and aninterface connected to the wedge, wherein the interface is configuredfor pushing the wedge in a first linear motion along the linear pathtoward the first distal end portion of the first facet plate and thesecond distal end portion of the second facet plate, wherein theinterface is configured for pulling the wedge in a second linear motionalong the linear path toward the first proximal end portion of the firstfacet plate and the second proximal end portion of the second facetplate, wherein the first distal end portion of the first facet plate andthe second distal end portion of the second facet plate move apart whenthe wedge is pushed in the first linear motion along the linear pathtoward the first distal end portion of the first facet plate and thesecond distal end portion of the second facet plate, and wherein thefirst distal end portion of the first facet plate and the second distalend portion of the second facet plate move apart when the wedge ispulled in the second linear motion along the linear path toward thefirst proximal end portion of the first facet plate and the secondproximal end portion of the second facet plate.
 18. The facet jointimplant of claim 17, wherein the interface is configured for removablyconnecting to a delivery device.
 19. The facet joint implant of claim17, further comprising an elongated connector extending through anopening within the hinge between the interface and the wedge.
 20. Thefacet joint implant of claim 17, wherein the first facet plate, thesecond facet plate, and the hinge comprise a monolithic structure.